Semiconductor device

ABSTRACT

As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the &#34;Lead-On-Chip&#34; or &#34;Chip-On-Lead&#34; structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of Ser. No. 990,272, filedDec. 14, 1992 now U.S. Pat. No. 5,358,904, which application is aDivisional application of Ser. No. 915,861, filed Jul. 20, 1992 (nowabandoned) which application is a Continuation application of Ser. No.690,551, filed Apr. 24, 1991 (now abandoned) which application is aContinuation Application of Ser. No. 409,332, filed Sep. 19, 1989 (nowU.S. Pat. No. 5,068,712).

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device and, moreparticularly, to a technology effective if applied to the package of alarge-scale integrated circuit of high integration.

In the prior art, the semiconductor chip is sealed up with a moldingresin so that it may be protected. Several methods are used to mountleads in position on the semiconductor chip before the sealing.

For example, a lead frame having tabs at its center is used and mountedbefore the semiconductor chip is sealed. In this prior art, there isknown a method of connecting electrode pads around the semiconductorchip with the corresponding inner leads through bonding wires.

The common problem among the semiconductor packages of the prior art isthat the metal lead frame is cracked along the mold parting linesproviding the exits of the lead lines.

Another problem is that the passages for moisture or contaminants in theatmosphere to steal along the metal lead wires from the outside into thesemiconductor chip are relatively short.

Moreover, the surface mounting type package is seriously troubled by theso-called "reflow cracking" problem that the moisture contained in thepackage is expanded by the heat of the solder reflow to crack thepackage.

Still another problem is that the bonding wires necessary for connectingthe inner leads with the electrode pads of the semiconductor chip cannotbe intersected partly because they are relatively long and partlybecause they are alternately assigned to input/output terminals.

In order to solve the above-specified problems, therefore, there hasbeen proposed in Japanese Patent Laid-Open No. 241959/1986(corresponding to E.P. Publication No. 0198194) a semiconductor devicein which a plurality of inner leads are adhered to the circuit formingsurface of a semiconductor chip through the semiconductor chip andinsulating films by an adhesive, in which the inner leads and thesemiconductor chip are electrically connected through bonding wires andin which common inner leads (or bus bar inner leads) are disposed in thevicinity of the longitudinal center line of the circuit forming surfaceof the semiconductor chip.

Also disclosed in Japanese Patent Laid-Open No. 167454/1985 or218139/1986 (corresponding to U.S. Ser. No. 845.332) is the packagestructure of the so-called "tabless lead frame type", in which the tabs(i.e., the die pads) mounting the chip are eliminated to mount the chipon the insulating films adhered to the leads (i.e., Chip On Lead) and inwhich the bonding pads of the chip and the leading ends of the leads areconnected through wires.

Also proposed in Japanese Patent Laid-Open No. 92556/1984 or 236130/1986is the package structure in which the leads are adhered to the uppersurface of the chip (i.e., Lead On Chip) by an adhesive and in which thebonding pads of the chip and the leading end portions of the leads areconnected through wires.

According to the above-specified package structure arranged with theleads on the upper or lower surface of the chip, the heat and moistureresistances of the package can be improved because the leads in thepackage can be elongated. Thanks to the elimination of the tabs,moreover, the contact between the resin and the leads is improved toimprove the reflow cracking resistance. As a result, even thelarge-sized chip can be packed in the package of the existing size.Moreover, this package structure is advantageous in reducing the wiringdelay because it can shorten the bonding wires.

SUMMARY OF THE INVENTION

We have investigated the aforementioned semiconductor devices of theprior art and have found the following problems:

(1) In the semiconductor device of the prior art, the inner leads areadhered to the circuit forming surface of the semiconductor chip throughthe semiconductor chip and the insulating films by the adhesive. Becauseof the large stray capacity between the inner leads and thesemiconductor chip, the semiconductor device has a problem that thesignal transmission rate is dropped by the large stray capacity toincrease the electrical noises.

(2) Because of the large area of the insulating films, the amount ofmoisture absorbed is increased so that the absorbed moisture is gasifiedand expanded in the package during the reflow, thus causing a problemthat the package cracking is established by the moisture expansion.

(3) Since the aforementioned insulating films are made of a resin ofpolyimide, the amount of absorbed moisture is increased so that theabsorbed moisture is gasified and expanded in the package during thereflow, thus causing the problem of package cracking.

(4) Since the aforementioned adhesive is made of an acrylic resin, it isdegraded by the pressure cracker test or the like, thus raising aproblem that the reliability is dropped by the electrical leakagebetween the leads and the corrosions of the aluminum electrodes.

(5) Since the circuit forming surface of the semiconductor chip is notcoated all over with the resin coating of polyimide for protectionsagainst alpha rays, there arises a problem that errors are caused by thealpha rays.

(6) The common inner leads (i.e., bus bar inner leads) are used asradiating plates, but the element having a large exothermic portion isnot covered all over with the inner leads. There arises a problem thatthe radiation is insufficient in an element of 1 watt or higher.

(7) Since the insulating films made of the aforementioned resin ofpolyimide has a large area, there arises a problem that thesemiconductor device is weak in the temperature cycle.

(8) The wire bonding is accomplished across the aforementioned innerleads (i.e., bus bar inner leads), thus raising a problem in poorproductivity.

(9) The aforementioned adhesive layer is so soft that the wire bondingconditions are difficult to set, thus raising the problem of poorproductivity.

(10) This problem of poor productivity is also caused by the poorworkability for mounting the insulating films on the semiconductor chip.

(11) Since the semiconductor chip is insufficiently fixed by theportions of the inner leads, it is moved in the resin sealing (ormolding) operation, thus raising a problem that the productivity ispoor.

An object of the present invention is to provide a technique forimproving the reliability of a semiconductor device.

An object of the present invention is to provide a technique for asemiconductor device to improve the signal transmission rate due to thestray capacity between the semiconductor chip and the leads and toreduce the electrical noises.

Another object of the present invention is to provide a technique for asemiconductor device to improve the radiating efficiency of the heatgenerated.

Another object of the present invention is to provide a technique for asemiconductor device to reduce the influences of the heat during thereflow.

Another object of the present invention is to provide a technique for asemiconductor device to reduce the influences of the heat in thetemperature cycle.

Another object of the present invention is to provide a technique for asemiconductor device to prevent the molding defects from being caused.

Another object of the present invention is to provide a technique for asemiconductor device, which has a package structure arranged with leadson the upper or lower surface of the chip, to reduce the parasiticcapacity to be established between the chip and the leads.

Another object of the present invention is to provide a technique for asemiconductor device to improve the productivity.

Another object of the present invention is to provide a technique toimprove the moisture resistance.

The foregoing and other objects and novel features of the presentinvention will become apparent from the following description to be madewith reference to the accompanying drawings.

Representatives of the invention to be disclosed herein will be brieflydescribed in the following:

1. A semiconductor device of the type, in which common inner leads areadhered to the vicinity of the center line taken in the X- orY-direction of the principal surface of a semiconductor chip throughinsulators for insulating the semiconductor chip electrically, in whicha plurality of signal inner leads are adhered to the principal surfaceof the semiconductor chip through insulators for insulating thesemiconductor chip electrically, and in which the inner leads, thecommon inner leads and the semiconductor chip are electrically connectedthrough bonding wires and sealed up with a mold resin, wherein theimprovement resides in that the gaps between the semiconductor chip atthe outer lead side than the portions bonded to the insulators and saidinner leads are wider than those from the portions bonded to theinsulators.

2. A semiconductor device according to the foregoing item 1, wherein thearea occupied by the insulators is at most one half of the area of thesemiconductor chip.

3. A semiconductor device according to the foregoing item 1, wherein thearea for bonding the insulators and the principal surface of thesemiconductor chip is practically minimized.

4. A semiconductor device according to each of the foregoing items 1 to3, wherein the insulators are molded of a resin containing a portion ofthe inner leads.

5. A semiconductor device according to each of the foregoing items 1 to4, wherein the material of the insulators satisfies at least two of thefollowing conditions:

(1) The saturated moisture absorption is equal to or less than that ofthe sealing resin;

(2) The dielectric constant is 4.0 or less for 10³ Hz at a temperaturefrom the room temperature to 200° C.;

(3) The Barcol hardness (GYZ J934-1) at 200 ° C. is 20 or more;

(4) The amount of a soluble halogen element is 10 ppm or less in thecase of the uranium and thorium contents of 1 ppb or less and in thecase of extraction at 120° C. for 100 hours;

(5) The contact between the semiconductor chip and the inner leads isexcellent;

(6) The thermal expansion coefficient is 20×10⁻⁶ /°C. or less; and

(7) The theremost resin has a glass transition temperature of 220° C. ormore.

6. A semiconductor device of the type, in which all of a plurality ofinner leads are so arranged on the principal surface of a semiconductorchip as to float from the principal surface of the semiconductor chip,in which the semiconductor chip is adhered and fixed to the deenergizedones of the inner leads, and in which the remaining inner leads and thesemiconductor chip are electrically connected through bonding wires andsealed up with a mold resin.

7. A semiconductor device of the type, in which a plurality of innerleads are so arranged on the principal surface of a semiconductor chipas to flat from the principal surface of the semiconductor chip, inwhich the side of the semiconductor chip opposite to the principalsurface is adhered and fixed through insulators by a portion of theinner leads, and in which the inner leads and the semiconductor chip areelectrically connected through bonding wires and sealed up with a moldresin.

8. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chipthrough insulators for insulating the semiconductor chip electrically,and in which the inner leads and the semiconductor chip are electricallyconnected through bonding wires, wherein the improvement resides: inthat radiating leads electrically insulated from the semiconductor chiphave their one-side ends held on the principal surface of thesemiconductor chip at the central portion of the longitudinal side ofthe package; and in that the other terminals of the radiating leads areextended to above the principal surface of the semiconductor chipoutside the package.

9. A semiconductor device according to the foregoing item 8, wherein theother ends of the radiating leads are extended to below the sideopposite to the principal surface of the semiconductor chip outside ofthe package.

10. A semiconductor device according to the foregoing item 8 or 9,wherein the one-side ends of the radiating leads are extended to abovethe exothermic portions of the principal surface of the semiconductorchip.

11. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chipthrough insulators for insulating the semiconductor chip electrically,and in which the inner leads and the semiconductor chip are electricallyconnected through bonding wires, wherein the improvement resides: inthat one-side ends of radiating leads electrically insulated from thesemiconductor chip are held on the central portion of the longitudinalside of the package and on the side opposite to the principal surface ofthe semiconductor chip; and in that the other ends of the radiatingleads are extended to above the principal surface of the semiconductorchip outside of the package or to below the side opposite to theprincipal surface of the semiconductor chip outside of the package.

12. A semiconductor device according to any of the foregoing items 8 to11, wherein the radiating leads are equipped at their outside withradiating plates.

13. A semiconductor device according to any of the foregoing items 6 to12, wherein common inner leads are arranged in the vicinity of the X- orY-directional center line of the principal surface of the semiconductorchip.

14. A semiconductor device according to any of the foregoing items 1 to12, wherein the bonding wires are coated with insulators.

15. A semiconductor device according to any of the foregoing items 1 to6 or 13, wherein the semiconductor chip has its principal surfacearranged with bonding pads which do not intersect with the bonding wiresarranged on the principal surface and the common inner leads.

16. A semiconductor device according to any of the foregoing items 1 to15, wherein the mold resin material is a resin composite which isprepared by blending a thermoset resin with 70 wt. % or more of asubstantially spherical inorganic filler having a particle sizedistribution of 0.1 to 100 microns, an average particle diameter of 5 to20 microns and the maximum packing density of 0.8 or more.

17. A semiconductor device according to the foregoing item 16, whereinthe mold resin material is composed mainly of at lease one of aphenol-set type epoxy resin, a resol type phenol resin and abismaleimide resin.

18. A semiconductor device according to the foregoing item 16 or 17,wherein the mold resin material is composed mainly of the resol typephenol resin or the bismaleimide resin as the the thermoset resin, andwherein its molding has a bending strength of 3 kgf/mm or more at 215°C.

19. A semiconductor device according to any of the foregoing items 16 to18, wherein the mold resin material contains as its inorganic fillerspherical molten silica having a particle size distribution of 0.1 to100 microns, an average particle diameter of 5 to 20 microns and themaximum packing density of 0.8 or more.

20. A semiconductor device according to any of the foregoing items 16 to19, wherein the mold resin material is blended as its inorganic fillerwith 67.5 vol % or more of substantially spherical molten silica havinga particle size distribution of 0.1 to 100 microns, an average particlediameter of 5 to 20 microns and the maximum packing density of 0.8 ormore, and wherein its molding has a linear expansion coefficient of1.4×10⁻⁵ /°C. or less.

21. A semiconductor device according to any of the foregoing items 16 to20, wherein the mold resin material has an extract of pH 3 to 7, in caseit is mixed with ion exchange water in an amount of ten times andextracted at 120° C. for 100 hours, an electric conductivity of 200μS/cm or less, and extractions of halogen ions, ammonia ions and metalions of 10 ppm or less.

22. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the adhesive is blended as a filler withspherical fine particles which have a constant particle diameter andwhich are selected from a thermoplastic resin or thermoset resin havinga softening temperature higher than the inorganic or adheringtemperature.

23. A semiconductor device of the type, according to the foregoing items1 to 22 in which a plurality of inner leads are either adhered to theprincipal surface of a semiconductor chip with an adhesive throughinsulators for insulating the semiconductor chip electrically orarranged in a state floating from the principal surface of thesemiconductor chip, and in which the inner leads and the semiconductorchip are electrically connected through bonding wires, wherein theimprovement resides: in that the semiconductor chip is coated with analpha ray shielding polyimide film at all its circuit forming regionsother than bonding pads; and in that the semiconductor chip is formedwith an insulating film on its portion to which are adhered at least theleading ends of the inner leads or suspension leads.

24. A semiconductor device according to the foregoing item 23, whereinthe insulators are made of a thermoset resin containing a printableinorganic filler.

25. A semiconductor device according to the foregoing item 23 or 24,wherein the area occupied by the insulators is at most one half of thechip area.

26. A semiconductor device according to any of the foregoing items 23 to25, wherein the semiconductor chip is formed with a polyimide film atits side opposite to the principal surface.

27. A semiconductor device according to any of the foregoing items 23 to26, therein the insulators are formed highly accurately by a waferprocess including the steps of: a solvent-peeling type dry film to asemiconductor wafer; exposing and developing the dry film in an ordinarymanner: applying a pasty insulator and burying it with squeezee; heatingto cure the film; and peeling the film.

28. A semiconductor device according to the foregoing item 26, whereinthe wafer process further includes the step of forming the insulators bydeveloping and exposing a solder resist dry film.

29. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that an insulating film is arranged on all orsome of the inner leads opposed and closest to the semiconductor chip.

30. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip as its principalsurface covered wholly or partially with a substance which is moreflexible or fluid than the mold resin to cover some or all of thebonding wires while the outside being sealed up with a resin.

31. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip has its principalsurface covered wholly or partially with a bonding resin which coverssome or all the bonding wires while the outside being sealed up with themold resin.

32. A semiconductor device according to the foregoing item 31, whereinthe outer surface of the mold resin covering the side of thesemiconductor chip other than the main surface is recessed to expose aportion of the semiconductor chip substantially to the outside.

33. A semiconductor device according to any of the foregoing items 30 to32 wherein common inner leads are disposed in the vicinity of the X- orY-directional center line of the principal surface of the semiconductorchip.

34. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip is formed with arecess or rise in its side other than the principal surface.

35. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip is formed with aplurality of grooves in its side other than the principal surface.

36. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the semiconductor chip is formed with arecess, a rise or a plurality of grooves in its side other than theprincipal surface while being left with a silicon oxide film.

37. A semiconductor device of the type, in which a plurality of innerleads are adhered to the principal surface of a semiconductor chip withan adhesive through insulators for insulating the semiconductor chipelectrically, and in which the inner leads and the semiconductor chipare electrically connected through bonding wires, wherein theimprovement resides in that the distance from the portions of the innerleads contacting with the semiconductor chip to the outer wall of apackage is made larger than the distance from the side of thesemiconductor chip opposite to the principal surface to the outer wallof the package.

38. A semiconductor device according to any of the foregoing items 1 to37, wherein the semiconductor chip is two in which the bonding pads tothe inner leads are disposed in mirror symmetry, and wherein the innerleads and the bonding pads of the semiconductor chip are electricallyconnected across the inner leads at the side of the principal surface ofthe two semiconductor chips and are sealed up with a mold resin.

39. A semiconductor device according to any of the foregoing items 34 to38, wherein common inner leads are arranged in the vicinity of the X- orY-directional center line of the semiconductor chips.

40. A semiconductor device according to any of the foregoing items 1 to39, wherein the surface opposed to a substrate mounting saidsemiconductor device is formed with at least one of radiating groovewhich has its two ends opened to the outside at the sides of thesemiconductor device.

41. A semiconductor device according to the foregoing item 40, whereinthe side of the semiconductor device opposite to the side formed withthe radiating groove is formed with a second radiating groove which isextended in the same direction of the first-named radiating groove andwhich has its two ends opened to the outside of the sides of thesemiconductor device.

42. A semiconductor device according to the foregoing item 41 or 42,wherein the mold resin in the bottom of the radiating grooves formed inthe surface opposed to the substrate mounting the semiconductor devicehas a thickness of 0.3 mm or less.

43. A semiconductor device according to any of the foregoing items 40 to42, wherein common inner leads are arranged in the vicinity of the X- orY-directional center line of the principal surface of the semiconductorchip.

44.A semiconductor device according to any of the foregoing items 40 to43, wherein the semiconductor devices are so packed in their mountingsubstrates that their radiating grooves merge into each other.

45. A semiconductor device wherein leads arranged in the upper or lowersurface of a chip packed in a package are partially folded outward withrespect to the upper or lower surface of the chip.

According to the means of the foregoing item 1, the inner leads are sostepped that the gaps between the semiconductor chip at the outer leadside than the portions bonded to the insulators and said inner leads arewider than those from the portions bonded to the insulators. The straycapacity between the semiconductor chip and the leads can be made lowerthan that of the prior art to improve the signal transmission rate andreduce the electrical noises.

According to the means of the foregoing item 2, the area of theprincipal surface of the semiconductor chip occupied by the insulatorsis at most one half of the area of the semiconductor chip so that themoisture absorption by the insulating films can be dropped to reduce theinfluences of the heat during the reflow and in the temperature cycle.

Since, moreover, the stray capacity between the semiconductor chip andthe leads is lower than that of the prior art, it is possible to improvethe signal transmission rate and to reduce the electrical noises.

According to the means of the foregoing item 3, the area for bonding theinsulators and the principal surface of the semiconductor chip ispractically minimized to minimize the moisture absorption by theinsulating films. As a result, it is possible to reduce the influencesof the heat during the reflow and in the temperature cycle. Since,moreover, the stray capacity between the semiconductor chip and theleads is lower than that of the prior art, it is possible to improve thesignal transmission rate and to reduce the electrical noises.

According to the means of the foregoing item 4, the insulators on theprincipal surface of the semiconductor chip are made of the resinmolding including a portion of the inner leads to sufficiently enlargethe distance between the semiconductor chip and the inner leads so thatthe stray capacity between the semiconductor chip and the leads is farlower than that of the prior art. As a result, it is possible to improvethe signal transmission rate and to reduce the electrical noises.

Since, moreover, the molding resin is selected as a material having agood matching with the sealing resin, it is possible to prevent thepeeling between the molding resin and the sealing resin (or mold resin).As a result, it is possible to reduce the leakage between the innerleads.

According to the means of the foregoing item 5, the optimum insulatorcan be selected by the semiconductor element.

According to the means of the foregoing item 6, the semiconductor chipis adhered and fixed to those of the inner leads, which are notenergized, whereas the remaining inner leads are arranged apart (i.e.,electrically insulated) therefrom on the principal surface of thesemiconductor chip. Since no insulating film is use, the moistureresistance can be improved. Moreover, the step of adhering theinsulating film is eliminated.

According to the means of the foregoing item 7, the plural inner leadsare arranged apart (or electrically insulated) from principal surface ofa semiconductor chip, and the side of the semiconductor chip opposite tothe principal surface is adhered and fixed through insulators by aportion of the inner leads, and in which the inner leads and thesemiconductor chip are electrically connected through bonding wires andsealed up with a mold resin. Since the inner leads are not adhered tothe principal surface of the semiconductor chip, this principal surfacecan be prevented from being broken or damaged. Since, moreover, noinsulating film is used on the principal surface of the semiconductorchip, it is possible to improve the moisture resistance.

According to the means of the foregoing item 8, radiating leadselectrically insulated from the semiconductor chip have their one-sideends held at the central portion of the longitudinal side of thepackage, and the other terminals of the radiating leads are extended toabove the principal surface of the semiconductor chip outside thepackage. As a result, it is possible to improve the radiating efficiencyof the heat of the exothermic portions of the semiconductor chip.

According to the means of the foregoing item 9, the other ends of theradiating leads of the means of the item 9 are extended to below theside opposite to the principal surface of the semiconductor chip outsideof the package. As a result, it is possible to improve the radiatingefficiency of the heat of the exothermic portions of the semiconductorchip.

According to the means of the foregoing item 10, the one-side ends ofthe radiating leads of the means of the foregoing item 9 are extended toabove the exothermic portions of the principal surface of thesemiconductor chip. As a result, it is possible to improve the radiatingefficiency of the heat of the exothermic portions of the semiconductorchip.

According to the means of the foregoing item 11, one-side ends ofradiating leads electrically insulated from the semiconductor chip ofthe means of the foregoing item 10 are held on the central portion ofthe longitudinal side of the package and on the side opposite to theprincipal surface of the semiconductor chip, and the other ends of theradiating leads are extended to above the principal surface of thesemiconductor chip outside of the package or to below the side oppositeto the principal surface of the semiconductor chip outside of thepackage, As a result, it is possible to improve the radiating efficiencyof the heat of the exothermic portions of the semiconductor chip.

According to the means of the foregoing item 12, the radiating leads ofthe means of any of the foregoing items 8 to 11 are equipped at theiroutside with radiating plates. As a result it is possible to furtherimprove the radiating efficiency of the heat of the exothermic portionsof the semiconductor chip.

According to the means of the foregoing item 13, common inner leads(i.e., bus bar inner leads) of the means of any of the foregoing items 1to 12 are arranged in the vicinity of the X- or Y-directional centerline of the principal surface of the semiconductor chip. As a result,the bonding wires of the reference voltage (V_(SS)) or the power sourcevoltage (V_(CC)) in the semiconductor chip can be wired within a smallarea without any shorting. It is also possible to improve theworkability of the wire bonding.

According to the means of the foregoing item 14, the bonding wires ofthe means of the foregoing item 13 are coated with insulators. As aresult, the bonding wires for connecting the signal line inner leads andthe semiconductor chip can be prevented from being shorted with thesignal inner leads.

According to the means of the foregoing item 15, the semiconductor chipof the means of the foregoing item 14 has its principal surface arrangedwith bonding pads (i.e., external terminals) which do not intersect withthe bonding wires arranged on the principal surface and the common innerleads (i.e., bus bar inner leads). As a result, the bonding wires forconnecting the signal line inner leads and the semiconductor chip can beprevented from being shorted with the signal inner leads.

According to the means of the foregoing items 16 to 21:

(1) The sealing material using as a filler the substantially sphericalmolten silica having a particle size distribution of 0.1 to 100 microns,an average diameter of 5 to 20 microns and the maximum packing densityof 0.8 or more has a lower molten viscosity and a higher materialfluidicity than the angular molten silica in current use. When in themolding operation, the gold (Au) wires or leads are neither deformed noris flown away the semiconductor chip. It is also possible to pack thenarrow gap of the package fully.

(2) Since the sealing material using the spherical molten silica islittle influenced in its molten viscosity and fluidicity, it is possibleto increase the loading thereby to reduce the thermal expansion of thematerial.

(3) An excellent reliability can be attained if the resol type phenolresin and polyimide resin used are highly pure.

(4) The sealing material using the highly pure resol type phenol resinand polyimide resin provides moldings of high heat resistance andexcellent mechanical strength at a high temperature. As a result, it ispossible to attain both a reflow resistance (to package cracking) incase the package absorbs moisture and a reliability in the moistureresistance and the resistance to thermal shocks after the reflow.

According to the means of the foregoing item 22, a filler of sphericalfine particles having a constant particle diameter is blended in theadhesive of the means of each of the foregoing items 1 to 21. As aresult, the gap between the semiconductor chip and the leads can becontrolled to a constant value (equal to the filler diameter) so thatthe dispersion of the capacity between the semiconductor chip and theleads can be reduced.

According to the means of the foregoing item 23, the semiconductor chipof the means of each of the foregoing items 1 to 21 is coated with analpha ray shielding polyimide film at all its circuit forming regionother than bonding pads, and the semiconductor chip is formed with aninsulating film on its portions to which are adhered at least theleading ends of inner leads or suspension leads. As a result, the wholecircuit forming region can be shielded from the alpha rays by the alpharay shielding polyimide film, and the semiconductor chip can be adheredand fixed by the insulating film.

Since, moreover, the insulating film is formed on the semiconductor chipat only the portions to which are adhered at least the leading ends ofthe inner leads and the suspension leads, it is possible to reduce thestray capacity between the semiconductor chip and the inner leads.

Incidentally, the wafer is not warped even if the thick insulators areformed by the wafer process but partially.

According to the means of the foregoing item 24, the insulating films ofthe means of the foregoing item 23 are made of a thermoset resincontaining a printable inorganic filler. As a result, the insulatingfilms can be made highly accurate in the wafer process.

According to the means of the foregoing item 25, the area occupied bythe insulating films of the foregoing item 23 or 24 is at most one halfof the chip area. As a result, the moisture absorption by the insulatingfilms can be dropped to reduce the influences of the heat during thereflow and the in the temperature cycle.

Since, moreover, the stray capacity between the semiconductor chip andleads can be made smaller than that of the prior art, it is possible toimprove the signal transmission rate and to reduce the electricalnoises.

According to the means of the foregoing item 26, the semiconductor chipof the means of each of the foregoing items 22 to 24 is formed with apolyimide film at its side opposite to the principal surface. As aresult, it is possible to prevent the cracking from being caused by theheat of the reflow.

According to the means of the foregoing item 27, the insulators of meansof each of the foregoing items 23 to 26 are formed highly accurately bya wafer process including the steps of: a solvent-peeling type dry filmto a semiconductor wafer; exposing and developing the dry film in anordinary manner; applying a pasty insulator and burying it withsqueezee; heating to cure the film; and peeling the film. Thus, theinsulators can be formed highly accurately by the batch process toimprove the productivity.

According to the means of the foregoing item 28, the insulators of themeans of the foregoing item 26 are formed by developing and exposing asolder resist dry film. As a result, the productivity can be improved.

According to the means of the foregoing item 29, the insulating film isformed in a lead frame state on all or some of the inner leads opposedand closest to the semiconductor chip. As a result, the insulating filmbetween the semiconductor chip and the inner leads of the means of theforegoing item 2 or 3 can be easily provided in an improvedproductivity.

According to the means of the foregoing item 30, the semiconductor chiphas its principal surface covered wholly or partially with a substancewhich is more flexible or fluid than the sealing resin (or mold resin)to cover some or all of the bonding wires while the outside being sealedup with a resin. As a result, the mold resin can be kept away fromdirect contact with the bonding wires to prevent the bonding wires frombeing repeatedly deformed by the relative deformations between thesemiconductor chip and the resin in the temperature cycle andaccordingly from being broken due to fatigue.

According to the means of the foregoing item 31, the semiconductor chiphas its principal surface covered wholly or partially with a bondingresin which covers some or all the bonding wires while the outside beingsealed up with the mold resin. As a result, the mold resin can be keptaway from, direct contact with the bonding wires to prevent the bondingwires from being repeatedly deformed by the relative deformationsbetween the semiconductor chip and the resin in the temperature cycleand accordingly from being broken due to fatigue.

According to the means of the foregoing item 32, the outer surface ofthe mold resin covering the side of the semiconductor chip of the meansof the foregoing item 31 other than the main surface is recessed toexpose a portion of the semiconductor chip substantially to the outside.The resin cracking during the reflow soldering operation can beprevented with neither poor moisture resistance of the bonding pads norwire disconnection in the temperature cycle.

Here, the word "substantially" imagines that there exists either such athin cover film of resin as will e inevitably formed on the surface of asemiconductor chip during the fabrication process or such a thin resinlayer as will be broken in case a steam pressure is built up in thepackage.

According to the means of the foregoing item 33, the common inner leads(or bus bar inner leads) of the means of each of the foregoing items 30to 32 are disposed in the vicinity of she X- or Y-directional centerline of the principal surface of the semiconductor chip. As a result,the bonding wires of the reference voltage (V_(SS)) or the Dower sourcevoltage (V_(CC)) in the semiconductor chip can be wired within a smallarea without any shorting. It is also possible to improve theworkability of the wire bonding.

According to the means of the foregoing item 34, the semiconductor chipis formed with a recess or rise in its side other than the principalsurface. As a result, the mold resin can be restricted by thesemiconductor chip to reduce the stress which is to be generated in themold resin portion of the corners of the non-circuit surface of thesemiconductor chip to be subjected to the reflow cracking, so that thisreflow cracking can be prevented.

According to the means of the foregoing item 35, the semiconductor chipis formed with a plurality of grooves in its non-circuit surface. As aresult, the mold resin can be restricted by the semiconductor chip toreduce the stress which is to be generated in the mold resin portion ofthe corners of the non-circuit surface of the semiconductor chip to besubjected to the reflow cracking, so that this reflow cracking can beprevented.

According to the means of the foregoing item 36, the semiconductor chipis formed with a recess, a rise or a plurality of grooves in its sideother than the principal surface while being left with a silicon oxide(SiO₂) film. Since the adhesion between the silicon oxide (SiO₂) filmand the mold resin is strong, it is possible to prevent the peeling ofthe mold resin from the side of the semiconductor chip opposite to thecircuit foxing surface. Thanks to the recess or rise or the pluralgrooves, moreover, it is possible to reduce the stress which isgenerated in the mold resin portion of the corner of the non-circuitside of the semiconductor chip by the mold resin so that the reflowcracking can be prevented.

According to the means of the foregoing item 37, the distance from theportions of the inner leads contacting with the semiconductor chip tothe outer wall of a package is made larger than the distance from theside of the semiconductor chip opposite to the principal surface to theouter wall of the package. As a result, the average flow speeds of theresin through the individual passages can be equalized to prevent theformation of voids and bending and shortage of packing of the bondingwires. Since, moreover, the resistances to the resin flows in theindividual passages are equalized, the semiconductor chip and the leadscan be prevented from changing to realize the molding of a highlyreliable package.

According to the means of the foregoing item 38, the semiconductor chipis two in which the bonding pads to the inner leads are disposed inmirror symmetry, and wherein the inner leads and the bonding pads of thesemiconductor chip are electrically connected across the inner leads atthe side of the principal surface of the two semiconductor chips and aresealed up with a mold resin. As a result, it is possible to package theelement having the twice capacity without changing the external shape.

According to the means of the foregoing item 39, the common inner leads(or bus bar inner leads) are arranged in the vicinity of the X- orY-directional center line of the semiconductor chips of the means ofeach of the foregoing items 34 to 38. As a result, the bonding wires ofthe reference voltage (V_(SS)) or the power source voltage (V_(CC)) inthe semiconductor chip can be wired within a small area without anyshorting. It is also possible to improve the workability of the wirebonding.

According to the means of any of the foregoing items 40 to 42, the heattransfer surface area of the resin-sealed type semiconductor device canbe enlarged to drop the heat resistance of the semiconductor device.

According to the means of the foregoing item 44, the semiconductordevices of the means of each of the foregoing items 40 to 43 are sopacked in their mounting substrates that their radiating grooves mergeinto each other. The cooling draft can be established in the directionof the radiating grooves and the second radiating grooves to cool theindividual semiconductor devices efficiently.

According to the means of the foregoing item 45, the leads are partiallyfolded outward with respect to the upper (or lower) side of the chip sothat the distance between the chip and leads can be enlarged to reducethe aforementioned parasitic capacity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially sectional perspective view showing a resin-sealedtype semiconductor device for sealing a DRAM according to Embodiment Iof the present invention;

FIG. 2 is a top plan view of FIG. 1,

FIG. 3 is a section taken along line I--I of FIG. 2;

FIG. 4 is a layout showing the schematic structure of the DRAM shown inFIG. 1;

FIG. 5 is an overall top plan view showing the lead frame shown in FIG.1;

FIGS. 6 and 7 are sections showing essential portions showing therelations between the inner leads and the semiconductor chip shown inFIG. 1;

FIG. 8 is a section showing the schematic structure of the resin moldingaccording to another embodiment of the insulator shown in FIG. 1;

FIG. 9 is a section taken along line II--II of FIG. 8;

FIG. 10 is a section showing the adhered portions of the resin moldingand the semiconductor chip of FIG. 8;

FIG. 11 is an exploded assembly view showing the relations among thesemiconductor chip, the insulator and the lead frame shown in FIG. 1;

FIGS. 12, 13 and 14 are diagrams for explaining the characteristics ofmold resin materials;

FIGS. 15 to 19 are diagrams for explaining a package optimized forinjecting the mold resin of the resin-sealed semiconductor device shownin FIG. 1 into a mold;

FIGS. 20, 21A, 21B, 22A and 22B are diagrams for explaining theschematic structure of a resin-sealed semiconductor device according toEmbodiment II of the present invention and a process for fabricating thesame;

FIGS. 23, 24a, 24b, 25, 26, 27, 28 are diagrams for explaining theschematic structure of a resin-sealed semiconductor device according toEmbodiment III of the present invention and a process for fabricatingthe same;

FIG. 29 is a partially sectional perspective view showing the schematicstructure of a resin-sealed type semiconductor device according toEmbodiment IV of the present invention;

FIG. 30 is a section taken along V--V of FIG. 29 and showing the statebefore the resin molding;

FIG. 31 is a section showing a resin-sealed type semiconductor deviceaccording to another embodiment before the resin molding in case aflexible/fluid substance of FIG. 29 is used:

FIGS. 32 and 33 are sections showing a resin-sealed type semiconductordevice according to another embodiment before the resin molding in casea flexible/fluid substance is used;

FIG. 34 is a section showing a resin-sealed type semiconductor deviceaccording to another embodiment before the resin molding in case aflexible/fluid substance is used;

FIG. 35 is a section showing the schematic section of a resin-sealedtype semiconductor device according to Embodiment V of the presentinvention;

FIGS. 36A, 37A, 38A, 39A, 40A and 41A are top plan views taken from theopposite side to the modified principal surface of the semiconductorchip of FIG. 35;

FIGS. 36B, 37B, 38B, 39B, 40B and 41B are sections taken along thetransverse center lines of FIGS. 36A, 37A, 38A, 39A, 40A and 41A;

FIG. 42 is a section showing another embodiment relating to theEmbodiment V;

FIG. 43 is a partially sectional perspective view showing the schematicstructure of a resin-sealed type semiconductor device according toEmbodiment VI of the present invention;

FIG. 44 is a section taken along line VI--VI of FIG. 43;

FIG. 45 is a partially sectional perspective view showing the schematicstructure of a resin-sealed type semiconductor device modified from theEmbodiment VI of the present invention;

FIG. 46 is a section taken along line VII--VII of FIG. 45;

FIG. 47 is a partially sectional perspective view showing the schematicstructure of a resin-sealed type semiconductor device modified from theEmbodiment VI of the present invention;

FIG. 48 is a section taken along line VIII--VIII of FIG. 47;

FIG. 49 is a partially sectional perspective view showing the schematicstructure of a resin-sealed type semiconductor device according toEmbodiment VII of the present invention;

FIG. 50 is a section taken along line IX--IX of FIG. 49;

FIG. 51 is a top plan view-showing the layout of the element of thesemiconductor chip of the Embodiment VII and the layout of the bondingpads BP;

FIG. 52 is an overall top plan view showing the lead frame of theEmbodiment VII;

FIG. 53 is a top plan view showing the schematic structure of the leadframe of a resin-sealed type semiconductor device according toEmbodiment VIII of the present invention;

FIGS. 54A, 54B and 54C are sections showing the semiconductor chipfixing portions of the resin-sealed type semiconductor device accordingto the Embodiment VIII of the present invention, respectively;

FIGS. 55, 56 and 57 are sections showing the modifications of theresin-sealed type semiconductor device according to the Embodiment VIIIof the present invention before the resin molding;

FIGS. 58 and 59 are layouts of the semiconductor chips of theresin-sealed type semiconductor device according to Embodiment IX of thepresent invention;

FIG. 60 is a section for explaining the package of the resin-sealed typesemiconductor device according to the Embodiment IX of the presentinvention;

FIG. 61 is a perspective view showing the side opposed to the wiringsubstrate of a resin-sealed type semiconductor device according toEmbodiment X;

FIG. 62 is a section taken along line XI--XI of FIG. 61;

FIG. 63 is a section showing a modification of the resin-sealed typesemiconductor device of the Embodiment X;

FIGS. 64, 65, 66 and 67 are sections showing other modifications of thesemiconductor device of the Embodiment X;

FIGS. 68 and 69 are sections showing the state in which the resin-sealedtype semiconductor device of the Embodiment X is packed in the wiringsubstrate;

FIG. 70 is an overall perspective view showing the schematic structureof the resin-sealed type semiconductor device for sealing the DRAMaccording to Embodiment XI of the present invention;

FIG. 71 is a partially sectional perspective view of FIG. 70;

FIG. 72 is a section taken along line XII--XII FIG. 74 and showing asemiconductor device according to one embodiment of the presentinvention;

FIG. 73 is a partially broken section taken along line XIII--XIII ofFIG. 74;

FIG. 74 is a general top plan view showing the semiconductor device;

FIG. 75 is a general top plan view of a semiconductor chip showing thecircuit block of the semiconductor device:

FIG. 76 is a section taken along line XIV--XIV FIG. 77 and showing asemiconductor device according to another embodiment of the presentinvention;

FIG. 77 is a general top plan view showing the semiconductor device;

FIG. 78 is a general top plan view of a semiconductor chip showing thecircuit block of the semiconductor device; and

FIG. 79 is a partially broken section showing a semiconductor deviceaccording to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be specifically described in the following inconnection with the embodiments thereof with reference to theaccompanying drawings.

Throughout all the drawings for explaining the embodiments, the portionshaving identical functions are designated at identical referencecharacters, and their repeated descriptions will be omitted.

Embodiment I

A resin-sealed type semiconductor device for sealing a DRAM according tothe embodiment I of the present invention is shown in FIG. 1 (inpartially sectional perspective view), in FIG. 2 (in top plan view) andin FIG. 3 (in section taken along line I--I of FIG. 2).

As shown in FIGS. 1, 2 and 3, a DRAM (i.e., a semiconductor chip) 1 issealed with an SOJ (Small Outline J-bend) type resin-sealed package 2.The DRAM 1 is made to have a large capacity of 16 (Mbits)×1 (bit) and arectangular area of 16.48 (mm)×8.54 (mm). This DRAM 1 is sealed with theresin-sealed package 2 of 400 (mil).

The DRAM 1 has its principal surface arranged mainly with a memory cellarray and a peripheral circuit. The memory cell array is arranged in amatrix form with a plurality of memory cells (or elements) for storinginformation of 1 (bit), as will be described in detail hereinafter. Theperipheral circuit is comprised of a direct peripheral circuit and anindirect peripheral circuit. The direct peripheral circuit is one fordirectly controlling the information writing and reading operations ofthe memory cells. This direct peripheral circuit includes a row-addressdecoder, a column address decoder and a sense amplifier. The indirectperipheral circuit is one for controlling the operations of the directperipheral circuit indirectly. This indirect peripheral circuit includesa clock signal generator and a buffer.

The principal surface of the DRAM 1, i.e., the surface arranged with thememory cell array and the peripheral circuit is arranged with innerleads 3A. Insulating films 4 are sandwiched between the DRAM 1 and theinner leads 3A. The insulating films 4 are made of a resin film ofpolyimide or the like. The individual surfaces of the insulating films 4at the sides of the DRAM 1 and the inner leads 3A are formed withadhesive layers. These adhesive layers are made of a resin such as apolyether amide-imide resin or an epoxy resin. The resin-sealed package2 of this kind adopts the LOC (Lead On Chip) structure in which theinner leads 3A are arranged over the DRAM 1. The resin-sealed typepackage 2 adopting this LOC structure can handle the inner leads 3Afreely without being restricted by the shape of the DRAM 1 so that itcan seal up the DRAM 1 having a size enlarged according to the freehandling. In other words, the resin-sealed package 2 adopting the LOCstructure can suppress the sealing (or package) size, even if the DRAM 1has its size enlarged according to the large capacity, thereby toenhance the packing density.

The inner leads 3A have their one-side ends made integral with outerleads 3B. These outer leads 3B are specified with signals to be appliedthereto, on the basis of the standards and are numbered. In FIG. 1, thelefthand foremost one is the 1st terminal, and the righthand foremostone is the 14th terminal. The righthand rear one (the terminal number ofwhich is shown at the inner lead 3A) is the 15th terminal, and thelefthand rear one is the 28th terminal. In short, the resin-sealed typepackage 2 is comprised of totally 24 terminals, i.e., the 1st to 6thterminals, the 9th to 14th terminals, 15th to 20th terminals and 23th to28th terminals.

The 1st terminal is one for a power source voltage V_(CC). This powersource voltage V_(CC) is at 5 (V) for operating the circuit, forexample. The 2nd terminal is a data input signal terminal (D): the 3rdterminal is an idle terminal; the 4th terminal is a write enable signalterminal (W) ; the 5th terminal is a row address strobe signal terminal(RE); and the 6th terminal is an address signal terminal (A₁₁).

The 9th terminal is an address signal terminal (A₁₀); the 10th terminalis an address signal terminal (A₀); the 11th terminal is an addresssignal terminal (A₁); The 12th terminal is an address signal terminal(A₂); and the 13th terminal is an address signal terminal (A₃). The 14thterminal is a power source voltage V_(CC) terminal.

The 15th terminal is a reference voltage V_(SS) terminal. This referencevoltage V_(SS) is at the reference level of 0 (V) of the circuit. The16terminal is an address signal terminal (A₄); the 17th terminal is anaddress signal terminal (A₅); the 18th terminal is an address signalterminal (A₆); the 19th terminal is an address signal terminal (A₇); andthe 20th terminal is an address signal terminal (A₈).

The 23th terminal is an address signal terminal (A₉); the 24th terminalis an idle terminal; the 25th terminal is a column address strobe signalterminal (CAS); the 26th terminal is an idle terminal; and the 27thterminal is a data output signal terminal. The 28th terminal is areference voltage V_(SS) terminal.

The other-side ends of the inner leads 3A are extended across the longersides of the rectangular DRAM 1 to the center of the DRAM 1. The otherends of the inner leads 3A have their extensions connected with bondingpads (or external terminals) BP arrayed at the center of the DRAM 1through bonding wires 5. These bonding wires 5 are made of aluminum (Al)but may be exemplified by gold (Au) wires, copper (Cu) wires or coatedwires which are prepared by coating metal wires with an insulatingresin. The bonding wires 5 are bonded by the method using the hotcontact bonding together with the ultrasonic vibrations.

Of the inner leads 3A, The 1st and 14th (V_(CC)) terminals 3A are madeintegral with each other, and their central portions of the DRAM 1 areextended in parallel with their longer sides (namely, the inner leads(V_(CC)) 3A are called the "common inner leads" or "bus bar innerleads"). Likewise, the 15th and 28th inner lead terminals (V_(SS)) 3Aare made integral with each other, and their central portions of theDRAM 1 are extended in parallel with their longer sides (namely, theseinner leads (V_(SS)) 3A are called the "common inner leads" or "bus barinner leads"). The inner leads (V_(CC)) 3A and the inner leads (V_(SS))3A are extended in parallel in the regions which are defined by theother-side leading ends of the remaining inner leads 3A. These innerleads (V_(CC)) 3A and inner leads (V_(SS)) 3A are so constructed as cansupply the power source voltage V_(CC) and the reference voltage V_(SS)in any position of the principal surface of the DRAM 1. In short, thisresin-sealed type semiconductor device is constructed to absorb thepower source noises easily and to speed up the operations of the DRAM 1.

The shorter side of the rectangular DRAM 1 is equipped with a chipsupporting lead 3C.

The inner leads 3A, the outer leads 3B and the chip supporting lead 3Care cut from the lead frame and are molded. This lead frame is made of aFe-Ni alloy (containing 42 to 50 (%) of Ni) or Cu.

The DRAM 1, bonding wires 5, inner leads 3A and chip supporting lead 3Cthus far described are sealed up with a mold resin 2A. In order to dropthe stress, this mold resin 2A is exemplified by an epoxy resin to whichare added a phenol hardener, silicone rubber and a filler. The siliconerubber has an action to drop the modulus of elasticity of the epoxyresin as well as the thermal expansion coefficient. The filler is madeof balls of silicon oxide and has an action to drop the thermalexpansion coefficient. On the other hand, the package 2 is formed in itspredetermined position with an index ID (in the form of a notch locatedat the lefthand end of FIGS. 1 and 2).

Next, the structure of the DRAM 1 sealed up with the resin-sealed typepackage 2 is schematically shown in FIG. 4 (in a chip layout).

As shown in FIG. 4, the DRAM 1 is arranged substantially all over itssurface with a memory cell array (MA) 11. The DRAM 1 of the presentembodiment I has its memory cell array coarsely divided into four memorycell arrays 11A to 11D, although not limitative thereto. As shown inFIG. 4, the two memory cell arrays 11A and 11B are arranged at the upperside of the DRAM 1 whereas the two memory cell arrays 11C and 11D arearranged at the lower side. Each of these four memory cell arrays 11A to11D is finely divided into sixteen memory cell arrays (MA) 11. In short,the DRAM 1 is arranged with sixty four memory cell arrays 11. Each ofthese sixty four memory cell arrays 11 has a capacity of 256 (Kbits).

Between every two of the sixty four memory cell arrays 11 of the DRAM 1,there is arranged a sense amplifier (SA) 13. This sense amplifier 13 isconstructed of a complementary MOSFET (i.e., CMOS). Of the four memorycell arrays of the DRAM 1, each of the memory cell arrays 11A and 11B isarranged at its lower end with a column address decoder (YDEC) 12.Likewise, each of the memory cell arrays 11C and 11D is arranged at itsupper end with a column address decoder (YDEC) 12.

Of the four memory cell arrays of the DRAM 1, each of the memory cellarrays 11A and 11C is arranged at its righthand end with a word driver(WD) 14, a row address decoder (XDEC) 15 and a unit mat controller whichare disposed sequentially from the left to the right. Likewise, each ofthe memory cell arrays 11A and 11C is arranged at its lefthand end witha word driver (WD) 14, a row address decoder (XDEC) 15 and a unit matcontroller 16, which are disposed sequentially from the right to theleft.

Each of the sense amplifier 13, column address decoder 12, word driver14 and row address decoder 15 described above constitutes of the directone of the peripheral circuits of the DRAM 1. This direct peripheralcircuit is one for directly controlling the memory cells which arearranged in the finely-divided memory cell arrays 11.

Peripheral circuits 17 and external terminals BP are interposed betweenthe memory cell arrays 11A and 11B and between the memory cell arrays11C and 11D of the four memory cell arrays of the DRAM 1. The peripheralcircuits 17 are exemplified by a main amplifier 1701, an output buffer1702, a substrate potential generator (i.e., V_(BB) generator) 1703 anda power source circuit 1704. Totally sixteen main amplifiers 1701 arearranged four at a unit. Totally four output buffers 1702 are arranged.

The external terminals BP are arranged at the center of the DRAM 1because the aforementioned resin-sealed type semiconductor device 2 isconstructed to have the LOC structure so that the inner leads 3A areextended to the center of the DRAM 1. The external terminals 1 arearranged from the upper to the lower sides of the DRAM 1 within theregions which are defined by the memory cell arrays 11A and 11C, and 11Band 11D. The signals to be fed to the bonding pads (or externalterminals) BP have been described before in connection with theresin-sealed type semiconductor device 2 shown in FIG. 4, and theirdescriptions will be omitted here. Since the inner leads 3A fed with thereference voltage (V_(SS)) and the power source voltage (V_(CC)) arebasically extended from the upper to the lower sides on the surface ofthe DRAM 1, the DRAM 1 is arranged the plural external terminals BP forthe reference voltage (V_(SS)) and the power source voltage (V_(CC)) inthe extending direction thereof. In short, the DRAM 1 is so constructedas can feed the reference voltage (V.sub. SS) and the power sourcevoltage (V_(CC)) sufficiently. The data input signals (D), the dataoutput signals (Q), the address signals (A₀ to A₁₁), the clock signalsand the control signals are concentrated at the center of the DRAM 1.

Peripheral circuits 18 are interposed between the memory cell arrays 11Aand 11C and the memory cell arrays 11B and 11D of the four memory cellarrays of the DRAM 1. These peripheral circuits 18 are exemplified at alefthand side by a row address strobe (RE) circuit 1801, a write enable(W) circuit 1802, a data input buffer 1803, a power source voltage(V_(CC)) limitter, 1804, an X-address driver (or logical stage) 1805, anX-redundancy circuit 1806, and an X-address buffer 1807. The righthandside of the peripheral circuits are exemplified by a column addressstrobe (CE) circuit 1808, a test circuit 1809, a VDL limitter 1801, aY-address driver (or logical stage) 1811, a Y-redundancy circuit 1812and a Y-address buffer 1813. The center of the peripheral circuits 18are exemplified by a Y-address driver (or drive stage) 1814, anX-address driver (or drive stage) 1815 and a mat selection signalcircuit (or drive stage) 1816.

The aforementioned peripheral circuits 17 and 18 (and 16) are used asthe indirect peripheral circuits of the DRAM 1.

Next, the detail of the lead frame will be described in the following.

The lead frame of the present embodiment I is equipped, as shown in FIG.1 and FIG. 5 (i.e., in a top plan view of the whole lead frame), withtwenty signal inner leads 3A₁ and two common inner leads 3A₂. The innerleads 3A (i.e., the signal inner leads 3A₁ and the common inner leads3A₂) are so stepped that the gap between the portions of the inner leads3A to be adhered to the insulating films (or members) 4 and thesemiconductor chip 1 is larger than the gap between the portion to bebonded to the insulating films (or members) 4 and the semiconductorchip 1. Thanks to the stepped structure of the inner leads 3A, the straycapacity between the semiconductor chip and the leads is smaller thanthat of the prior art. As a result, it is possible to improve the signaltransmission rate and to drop the electrical noises.

On the other hand, the adhesion between the principal surface of thesemiconductor chip 1 and the insulating film 4 and the adhesion betweenthe insulating film 4 and the inner leads 3A are effected by means of anadhesive 7, as shown in FIG. 6. Alternatively, this adhesive 7 may beused not for adhering the principal surface of the semiconductor chip 1and the insulating film 4 but only for adhering the insulating film 4and the inner leads 3A, as shown in FIG. 7.

Incidentally, the inner leads 3A can attain the aforementioned effectseven if they are applied to a package having none of the common innerleads 3A₂.

In the predetermined positions of the lead frame, as shown in FIGS. 1and 5, there are disposed the chip supporting (or suspending) leads 3Cwhich are not supplied with any electric power but for adhering andfixing the principal surface of the semiconductor chip 1.

Since the semiconductor chip 1 is firmly fixed by adhering and fixingthe principal surface of the semiconductor chip 1 by means of thesuspending leads 3C of no power supply, it is possible to improve thereliability and the moisture resistance of the semiconductor device.

Next, the detail of the insulating films 4 will be described in thefollowing.

The area of the principal surface of the semiconductor chip 1 occupiedby the insulating films 4 is at most one half of the area of thesemiconductor chip 1. Since the area of the insulating films 4 is thusmade at most one half of the area of the semiconductor chip 1, themoisture absorption by the insulating films 4 can be reduced to preventthe influences of both the heat during the reflow and the steam which isgenerated by the heat of the temperature cycle. In other words, thepackage can be prevented from being cracked to improve the reliabilityof the semiconductor device.

Since, moreover, the stray capacity between the semiconductor chip 1 andthe leads is smaller than that of the prior art, it is possible toimprove the signal transmission rate and to drop the electrical noises.

Still moreover, the aforementioned effects can be made more prominent bypractically minimizing the area of bonding the insulating films 4 andthe principal surface of the semiconductor chip 1. On the other hand,the leakage between the leads can be reduced because only the portionsof the inner leads to be adhered to the semiconductor chip are coveredwith the insulating films.

On the other hand, the insulating films 4 over the principal surface ofthe semiconductor chip 1 may be modified, as shown in FIG. 8, such thata resin molding 6 containing portions of the aforementioned inner leads3A is used to sufficiently enlarge the gap between the semiconductorchip 1 and the inner leads 3A thereby to reduce the stray capacitybetween the semiconductor chip 1 and the inner leads 3A.

Thus, the resin molding 6 and the mold resin 2A can be made of thematerial of good affinity so that the leads can be less peeled at theirinterfaces.

The adhesion between the resin molding 6 and the semiconductor chip 1may be effected by means of the adhesive 7, as shown in FIG. 10.

The base material of the insulating films 4 and the resin molding 6 aremolded of: one or more major components, which are selected from anepoxy resin, a BT (Bismaleimide Triazine) resin, a phenol resin (i.e.,resol) and a polyimide resin (e.g., aromatic polyimide or cycloaliphaticpolyimide containing ether and carbonyl bonds; and an inorganic filler,a fibrous hardener or various additives, if necessary.

Other examples of the base material of the insulating films 4 and theresin molding 6 are molded of: a major component of a thermoplasticresin such as cycloaliphatic polyimide, polyester, polysulfone, aromaticpolyether amide, aromatic polyester imide, polyphenylene sulfide,polyamide-imide or its modified, polyether etherketone, polyethersulfone or polyether amine-imide; and an inorganic filler, fibers and anadditive, if necessary.

On the other hand, the adhesive for bonding the insulating films 4 orthe resin molding 6 to the inner leads 3A and the semiconductor chip 1can be selected from one of: an epoxy resin, a BT resin, a phenol resin(or resol), a polyimide resin, an isomelanic resin and a silicon resin;a thermoset resin modified from the above-specified resins; and athermoplastic resin such as aromatic polyether amide,polyether-ether-ketone, polysulfone, aromatic polyester imide, polyesteror cycloaliphatic polyimide.

In the face mounting package type integrated circuit such as SOJ, thevapor-phase reflow solder method or the infrared reflow solder method isused in the case of solder packaging on a printed circuit board (PCB).In this case, however, the moisture in the package may be gasified andexpanded by the reflow temperature (at 215° to 260° C.) to peel theadhesion at the chip interface until the internal pressure in the peeledfaces is raised to crack the sealing resin.

Since the LOC structure is made by bonding the inner leads 3A and thesemiconductor chip 1 with the insulating films 4 and the resin molding6, the aforementioned phenomena are accelerated by the moistureabsorption of the insulating films 4 or the resin molding 6. Foravoiding the phenomena, therefore, it is effective to reduce the volumeof the insulating films 4 thereby to decrease the moisture absorption.

The lower limit of the bonded area is that which can stand the externalforce to be borne at the wire bonding step and the resin molding step.

Here will be examined the physical properties of the insulator of theaforementioned insulating films 4 or the resin molding 6.

The bonding insulating material to be used between the inner leads 3Aand the semiconductor chip 1 of the semiconductor device having the LOCstructure or the COL (Chip On Lead) structure has to satisfy at leasttwo of the following seven conditions:

(1) The saturated moisture absorption is equal to lower than that of thesealing resin;

This condition is effective for preventing the resin cracking when inthe vapor-phase solder (VPS).

(2) The dielectric constant is 4.0 or less (at 10³ Hz at the roomtemperature to 200° C.);

This condition reduces the stray capacity between the inner leads andthe semiconductor chip.

(3) The Barcol hardness at 200° C. is 20 or more;

This condition improves the wire bonding properties.

(4) The contents of U and Th are 1 ppb or less, and the amount of ansoluble halogen extracted at 120° C. for 100 hours is 10 ppm or less;

This condition is effective for preventing the soft error and improvingthe moisture resistance.

(5) The contactness of the semiconductor chip and the inner leads isexcellent;

This condition can retain the wire bonding property, improve themoisture resistance and prevent the current leakage between the innerleads.

(6) The linear thermal expansion coefficient is 20×10⁻⁶ /°C. or less;and

This condition reduces the warpage, in case an insulating material isbonded to the inner leads 3A, to improve the bondability to thesemiconductor chip at a subsequent step.

(7) The glass transition temperature Tg is 220° C. or higher in the caseof the thermoplastic resin.

This condition is effective for preventing the material having a glasstransition temperature Tg of 220° C. or lower from being thermallydeformed at a high temperature (e.g., 215° C.) in the reflow solder tocause a package cracking.

Examples of the material satisfying at least two of the above-specifiedconditions will be described in the following.

For example, the film prepared by the following process was the materialsatisfying the above conditions except the item (1): The processincludes: the step of roughing the two sides of the Kapton 500 H (i.e.,the polyimide film produced by Du Pont or Upilex S (i.e., the polyimidefilm produced by Ube Kosan K. K.); and the step of coating the two sideswith 25 microns of polyether amide having a glass transition temperatureTg of 220 or more.

The conditions (1) to (6) were satisfied by the film which was preparedby applying and drying an adhesive of 10 to 25 microns, which wasselected from an epoxy resin, a resol resin, an isomelamine resin, aphenol-modified epoxy resin and an epoxy-modified polyimide resin, tothe two sides of a bismaleimide, epoxy or epoxy-modified polyimide filmof 125 microns reinforced by highly pure quartz fibers or aramid fibers.

On the other hand, the following film satisfied all the conditions andwas featured in its low moisture absorbability and small dielectricconstant. The film was prepared: by improving the adhesiveness of thetwo sides of the film of Teflon PFA (i.e., a copolymer oftetraethylenefluoride-perfluoroalkoxy, Teflon EFP (i.e., a copolymer oftetraethylenefluoride-perhexapropylenefluoride) or Kapton F-type (i.e.,the product of Toray and Du Pont, the Kapton film having its two sidesthinly coated with the Teflon FEP); and by coating the two sides of thefilm with an adhesive selected from an epoxy resin, a resol resin, anaromatic polyetheramide resin and a polyimide precursor.

Here will be described the method of adhering and fixing thesemiconductor chip 1 to the lead frame 3 through the insulating films 4by means of an adhesive.

As shown in FIG. 11 (in a development presenting the relations among thelead frame 3, the insulating films 4 and the semiconductor chip 1), theinsulating films 4 are divided and adhered to those portions of theprincipal surface of the semiconductor chip 1, which face the signalinner leads 3A, the common inner leads 3A₂ and the suspending leads 3C,by means of the adhesive 7 (shown in FIGS. 1 and 6). Next, as shown inFIG. 6, the signal inner leads 3A₁, the common inner leads 3A₂ and thesuspending leads 3C of the lead frame 3 are fixedly adhered by theadhesive 7.

The examples of the mold resin material (or resin) will be described inthe following:

(1) The resin composite to be used is exemplified by a thermoset resinwhich is blended with 70 wt. % of a substantially spherical inorganicfiller having a particle size distribution of 0.1 to 100 microns, anaverage particle diameter of 5 to 20 microns and the maximum packingdensity of 0.8 or more.

The resin component in this case may be any of epoxy, resol orpolyimide.

Thus, the mold resin material using the above-specified sphericalinorganic filler (e.g., molten silica) can be more blended to reduce thethermal expansion of the material, because its material exerts littleinfluence upon the molten viscosity and fluidicity, as shown in FIG. 12(plotting the relation between the packing density of the filter and thefluidicity). By increasing the loading of the filler, moreover, thethermal stress of the moldings can be dropped, as shown in FIG. 13(plotting the relations between the amount of synthesis of the fillerand the physical properties of the moldings) and FIG. 14 (plotting therelations between the amount of synthesis of the filler and the thermalstress). This improves the cracking resistance to a satisfactory extent.

Thus, it is possible to prevent a semiconductor device, which has anespecially fine structure such as the LOC structure, from being deformedor damaged when it is to be molded.

(2) The resin compound to be used is comprised mainly of at least onekind of a highly pure phenol-set type epoxy resin, resol type phenolresin and bismaleimide resin.

The properties of the set device in case the an unpurified resol resinis used are highly different from those of the purified device such thatthe bulk resistance is different by three figures or more at 140° C., astabulated in Table 1 (as located at the tailing page). Because of muchionic impurity, moreover, there is also found a large difference in theelectric conductivity of an extracted liquid.

The purified resol resin was produced, for example, by pouring 500 g ofphenol, 550 g of formalin of 30% and 5 g of zinc acetate as a hardenerinto a flask, by gradually agitating and heating them, and bycirculating and heating them at 90° C. for 60 minutes. After this, theinside of the flask was evacuated to 20 mmHg, and the condensate and theunreacted components were removed. Next, 300 g of acetone was added todissolve the reaction products, and pure water was added to agitate themviolently at 50° C. for 30 minutes. After the cooling, the upper waterlayer was removed, and the reaction products were dissolved again into300 g of acetone. Pure water was then added to agitate them violently at50° C. for 30 minutes. After the cooling, the upper water layer wasremoved. These cleaning operations were repeated five times. After eachof these cleaning operations, the reaction products were partially takenout and dried at 40° C. for 48 hours under an evacuated condition, toproduce six kinds of resol type phenol resins of different degrees ofrefinement.

The number of purifications, the melting point and the settingcharacteristics of the resol type phenol resins thus obtained; theanalytical results of the hydrogen ion density (pH) and the electricconductivity of the extracted water, which was prepared by adding 50 gof pure water to 50 g of resol type phenol resins and by heating them at120° C. for 120 hours; and the analytical result of the concentration ofthe ionic impurities extracted are tabulated in Table 2 (as located atthe trailing page).

As is apparent from Table 2, the resol type phenol resins having beensubjected to the aforementioned cleaning operations by five timescontain remarkably small amounts of ion impurities.

Thus, the purifications can improve the reliabilities in the moistureresistance of the moldings, the hot lifetime of the Au/Al bondedportions, and the characteristics of the element due to the differencesin the aforementioned characteristics.

(3) The molding resin materials to be used as exemplified by theexamples 2 and 3 of Table 1, which are comprised mainly of resol typephenol resins or bismaleimide resins of high purity and whose moldingshave a bending strength of 3 kgf/mm² or more at 215° C.

Since the sealing materials using the resol type phenol resins orpolyimide resins of high purity have a high heat resistance for theirmoldings and a bending strength of 3 kgf/mm² or more at 215° C., thereflow resistance (to package cracking) in the case of the packageshaving absorbed the moisture and the reliabilities in the moistureresistance and the resistance to the thermal shocks are improved to aremarkably satisfactory extent.

(4) The inorganic filler to be blended into the base resin of theforegoing item (2) or (3) is exemplified by any of the Examples 1, 2 and3 of Table 1, i.e., substantially spherical silica having a particlesize distribution of 0.1 to 100 microns, an average particle diameter of5 to 20 microns and the maximum packing density of 0.8 or more.

Thus, the sealing material using the above-specified spherical moltensilica has its molten viscosity and fluidicity little influenced so thatits thermal expansion can be dropped by increasing its loading. As aresult, the package acquires an excellent cracking resistance inaddition to the effects of the foregoing item (2) and (3).

(5) The aforementioned resin sealing material is a composite, in whichmore than 67.5 vol % of spherical molten silica having a particle sizedistribution of 0.1 to 100 microns, an average particle diameter of 5 to20 microns and the maximum packing density of 0.3 or more is blended asthe inorganic filler and whose molding has a linear expansioncoefficient of 1.4×10⁻⁵ /°C. This resin sealing material is exemplifiedby any of the Examples 1, 2 and 3 of Table 1.

Thus, the aforementioned effects of the spherical molten silica can befurther improved.

(6) The aforementioned resin sealing material is exemplified by any ofthe Examples 1, 2 and 3 of Table 1, which is mixed with ion exchangewater in an amount of ten times, and which has a pH of 3 to 7 as anextracted liquid, in case it is extracted at 120° C. for 100 hours, anelectric conductivity of 200 μS/cm and an extraction of ions of halogen,ammonia and metal of 10 ppm or less.

Next, one experiment of the Examples (1) to (6) of the above-specifiedresin sealing materials will be described in the following.

Three kinds of resin sealing materials were prepared, as tabulated inTable 1: by using an epoxy resin, the resol type phenol resin(Example 1) and the bismaleimide resin (Example 2) as the base materialof the thermoset resin; by adding to this base material both sphericalmolten silica having a particle size distribution of 0.1 to 100 microns,an average particle diameter of 5 to 20 microns and the maximum packingdensity of 0.90 as a filler and a variety of additives; by melting andheating the resultant mixture by a biaxial roll heated to about 80° C.;and by pulverizing the heated mixture after a cooling.

Next, each of the resin sealing materials was used to mold asemiconductor device having the LOC structure shown in FIG. 1, i.e., the16MDRAM by a transfer molding machine. The molding process wasaccomplished at a mold temperature of 180° C., under a transfer pressureof 70 kgf/mm² and for a molding period of 90 secs.

According to the experiment, the following effects could be attained:

(1) The sealing material, which used as its filler the substantiallyspherical molten silica having the particle size distribution of 0.1 to100 microns, the average particle diameter of 5 to 20 microns and themaximum packing density of 0.8 or more, had a lower molten viscosity anda better fluidicity than the sealing material using the generallyexisting square molten silica. During the molding process, therefore,the bonding wires 5 of Au or the like and the lead frame 3 were neitherdeformed or forced the semiconductor chip 1 to flow. In addition, thesealing material could fill up the narrow gap of the packageexcellently.

(2) The above-specified spherical molten silica exerted little influenceupon the molten viscosity and fluidicity of the material so that thethermal expansion of the material could be dropped by increasing theloading of the molten silica. As a result, the package had an excellentcracking resistance.

(3) In the semiconductor sealing material of the prior art, the epoxyresin was used, but the phenol resin or the polyimide resin were notused, because the latter two resins contained many ionic impurities andwere inferior in electric characteristics and the reliabilities in themoisture resistance so that they were not practical. If, however, ahighly pure resol type phenol resin or polyimide resin was used,satisfactory reliabilities could be attained.

(4) The sealing resin using the highly pure resol type phenol resin orpolyimide resin had a high heat resistance in its molding form and wasexcellent especially in the mechanical strength at a high temperature.As a result, the sealing resin was remarkably excellent either in thereflow resistance (to package cracking) in case the package absorbedmoisture or in the reliabilities in the moisture resistance and theresistance to the thermal shocks after the reflow.

Here will be described means for preventing formation of voids andbending and charge shortage of the bonding wires when the resin sealingmaterial is to be poured into a mold.

As shown in FIG. 1, the plural inner leads 3A are adhered to theprincipal surface of the semiconductor chip 1 through the insulatingfilms 4 for electrically insulating them from the semiconductor chip 1,by means of the adhesive 7. The inner leads 3A and the semiconductorchip 1 are electrically connected through the bonding wires 5 and aresealed up with the resin, thus producing the 16MDRAM. In this 16MDRAM,as shown in FIG. 15 (presenting the section of an essential portion ofFIG. 1), the package structure is made such that the distance H₁ betweenthe portion of the inner leads 3A adhered to the semiconductor chip 1and the outer wall of the package 2 is larger than the distance H₂between the side of the semiconductor chip opposite to thecircuit-formed side and the outer wall of the package.

Thanks to this package structure, as shown in FIG. 16 (presenting thesection of a model of FIG. 15), FIG. 17 (presenting the section takenalong line III--III of FIG. 16) and FIG. 18 (presenting the sectiontaken along line IV--IV of FIG. 16), the relations among the depths h₃₁and h₃₂ of flow paths of the upper portions of the inner leads 3A, thedepth h₂ of an intermediate portion between the inner leads 3A and thesemiconductor chip 1, and the depth h₁ of a flow path of the lowerportion of the semiconductor chip 1 are expressed by the followingEquations:

    h.sub.1 =h.sub.2 =(h.sub.c -t.sub.c -2W.sub.f t.sub.f /W.sub.c)/2(1+W/W.sub.c); h.sub.31 =h.sub.c -2h.sub.10r2 -t-t.sub.c ;

and

    h.sub.32 =h.sub.10r2 +t,

wherein:

h_(c) : Cavity depth;

t_(c) : Chip thickness;

t_(f) : Lead frame thickness;

W_(c) : Cavity width; and

W_(f) : Length of the lead frame floating from the chip.

The above-specified Equations are graphically plotted in FIG. 19.

Thus, the resin flow passage of the package 2 is divided into three: theupper flow path of the inner leads 3A; the intermediate flow pathbetween the inner leads 3A and the semiconductor chip 1; and the lowerflow path of the semiconductor chip 1. The individual flow path depthsand the resin flow path structures are so set as to equalize the averageresin flow speeds in the individual flow paths. As a result, the averageresin flow speeds in the flow paths, as indicated at circled numerals 1,2 and 3 in FIG. 17, can be equalized to prevent the generation of voids,the bending of the bonding wires (of Au) and the packing shortage.

Since, moreover, the average flow speeds of the flow paths designated atthe circled numerals 1, 2 and 3 are equal, the semiconductor chip 1 andthe inner leads 3A can be prevented from being deformed so that a highlyreliable package can be produced.

Embodiment II

In the semiconductor integrated circuit device according to theEmbodiment II of the present invention is constructed, as shown in FIG.20, FIGS. 21A and 21B and FIGS. 22A and 22B, the insulating films 4adhered to the principal surface of the semiconductor chip 1 of theforegoing Embodiment I are modified such that insulating films 4A arearranged all over or partially of those sides of the signal inner leads3A₁ and the common inner leads 3A₂, which are located in the closestposition to face the semiconductor chip 1.

More specifically, as shown in FIG. 20, the aforementioned insulatingfilms 4A are placed in advance all over the most closest sides of thesignal inner leads 3A₁ and the common inner leads 3A₂ facing theprincipal surface of the semiconductor chip 1 and are then fixedlyadhered to the semiconductor chip 1, when assembled.

The lead frame 3 thus carrying the insulating films 4A is manufacturedaltogether with the signal inner leads 3A₁, the common inner leads 3A₂and the insulating films 4A by adhering the insulating films 4 to thatwhole principal surface of the thin sheet for the inner leads, which isthe closest to face the semiconductor chip 1, and by shaping and cuttingthe insulating films 4 by a press.

Thus, the area of the insulating films 4 can be reduced. Moreover, thesignal inner leads 3A₁, the common inner leads 3A₂ and the insulatingfilms 4A can be held in predetermined positions. Furthermore, the signalinner leads 3A₁ and the common leads 3A₂ can be prevented from anyleakage because no insulating film 4 is interposed inbetween.

Here, these insulating films 4 can be less influenced by the thermalstress, if divided into a plurality or four sheets, than they areadhered in a single sheet.

As shown in FIG. 21A, moreover, of the whole (back) side facing andclosest to the principal surface of the semiconductor chip 1, only theside portions corresponding to the signal inner leads 3A₁ and the commonleads 3A₂ are arranged with the insulating films 4B. Then, the area ofthe semiconductor chip 1 to be occupied by the insulating films 4 can beminimized.

The lead frame 3 with the insulating films 4B occupying the minimum areaof the semiconductor chip 1 is prepared, as shown in FIG. 21B, byadhering four sheets of insulating films 4 having holes a inpredetermined positions, to the whole sides of the signal inner leads3A₁ and the common leads 3A₂ facing and closest to the principal surfaceof the semiconductor chip 1, and by shaping and cutting them by a pressto adhere the insulating films 4B to only the positions corresponding tothe bonding portions of the signal inner leads 3A₁ and the common leads3A₂.

As compared with the Embodiment shown in FIG. 20, the amount of theinsulating films can be made smaller to reduce the moisture absorption.Moreover, the semiconductor chip 1 can be fixed more easily with thesuspending leads.

In the embodiment shown in FIG. 21A, the insulating films 4A arearranged only in the portions corresponding to the bonding portions butmay be arranged partially in other portions, if necessary.

As shown in FIG. 22A, on the other hand, the insulating films 4A shownin FIG. 20 are also arranged with insulating films 4C to extend andintersect the common inner leads 3A₂ and the signal inner leads 3A₁.

The inner leads 3A with the insulating films 4C are prepared, as shownin FIG. 22B, by forming one sheet of insulating film 4 having holes bleaving only the portions corresponding to the signal inner leads 3A₁,and by cutting the insulating film 4 along the longitudinal center lineinto two halves. These two insulating film halves 4C are adhered to thecommon inner leads 3A₂ and the signal inner leads 3A₁.

Thus, it is sufficient to cut the insulating film 4 in advance in thepredetermined pattern to form the insulating films 4C and to adhere theinsulating films 4C to the common inner leads 3A₂ and the signal innerleads 3A₁. As a result, the method of preparing the insulating films 4Ccan be facilitated. Since, moreover, the insulating films 4C are adheredto the common inner leads 3A₂ and the signal inner leads 3A₁, theleading ends of the signal inner leads 3A₁ can be flattened tofacilitate the subsequent working steps.

The adhesions between the insulating films 4C and the common inner leads3A₂ and the signal inner leads 3A₁ are effected by the contact hotbonding in the case of a thermoplastic adhesive and are effected by thesettling after the tack holding in the case of a thermoset adhesive.

Incidentally, the insulating films 4A, 4B and 4C shown in FIGS. 20, 21Aand 22A may be either wider or narrower than the inner leads.

As is now apparent from the description made above, according to thepresent embodiment II, the insulating films 4 to be sandwiched betweenthe semiconductor conductor chip 1 and the signal inner leads 3A₁ andthe common leads 3A₂ are far less than those of the prior art so thatthe amount of moisture to be absorbed by the semiconductor device can bereduced even if the device is held in a wet circumstance for a longtime. As a result, the vapor pressure in the semiconductor device duringthe solder reflow step can be dropped to provide a semiconductor devicefreed from the resin cracking.

Embodiment III

In the semiconductor integrated circuit device according to theEmbodiment III of the present invention, as shown in FIG. 23, the wholeregion of the principal surface of the semiconductor chip 1 except thebonding pads BP of the principal surface of the semiconductor chip 1 ofthe foregoing Embodiment I is coated with an alpha ray shieldingpolyimide film 8, and the principal surface of the semiconductor chip 1is further formed with insulating films 4D on its portions to which atleast the signal inner leads 3A₁ and the common inner leads 3A₂ are tobe adhered.

The alpha ray shielding polyimide film 8 has a thickness of 2.0 to 10.0microns.

The insulating films 4D have a thickness of 75 microns or more. Theresin suited for the insulating films 4D is exemplified by a thermosetresin containing a printable inorganic filler.

The area occupied by the insulating films 4D is at most one half of thatof the semiconductor chip 1.

The semiconductor chip 1 is further formed with a polyimide film 9 onthe side opposed to its principal surface.

With reference to FIGS. 23 and 24A (presenting the flow chart offabrication and the sections of the individual steps), there will bedescribed one embodiment of the method of coating the whole region ofthe principal surface of the semiconductor chip 1 except the bondingpads BP of the principal surface of the semiconductor chip 1 with thealpha ray shielding polyimide film 8 and forming the insulating films 4Don the principal surface of the semiconductor chip 1 on its portions towhich at least the signal inner leads 3A₁ and the common inner leads 3A₂are to be adhered.

First of all, the alpha ray shielding polyimide film 8 is applied to thewhole region of a silicon wafer 10, as shown in FIG. 25 (presenting thetop plan view of the principal surface of the silicon wafer). Afterpartially set, the polyimide film 8 is photoetched to expose the bondingpads (or external terminals) BP to the outside (as indicated at Step 101in FIG. 24A).

Next, a solvent-peeling type dry film A is adhered (at Step 102). Thissolvent-peeling type dry film A is exposed (at Step 103) to apredetermined pattern and then developed (at Step 104) to form a hole B.

Next, a pasty insulating material (or printing paste) C is applied,buried with (printing) squeeze and cured (at Steps 105, 106 and 107).Then, the solvent-peeling type dry film A is peeled to form theinsulating films 4D. After this, a dicing is accomplished along thesolid lines over the silicon wafer 10 shown in FIG. 25, thus completingthe semiconductor chip with the insulating films 4D.

Another embodiment of the method of forming the aforementioned alpha rayshielding polyimide film 8 and the insulating films 4D is shown in FIG.24B (presenting the fabrication flow chart and the sections of the chipat the individual steps). As shown, the alpha ray shielding polyimidefilm 8 is applied to the whole region of the silicon wafer 10 and isphoto-etched to expose the bonding pads (or external terminals) BP Step201 in FIG. 24B).

Next, a dry film D for solder resists is adhered (at Step 202). Thissolder resist dry film D is exposed (at Step 203) to a predeterminedpattern and is developed (at Step 204) to form the insulating films 4D.After this, a dicing is accomplished along the solid lines of thesilicon wafer 10 shown in FIG. 25 to complete the semiconductor chipwith the insulating films 4D.

Incidentally, the silicon wafer 10 is not warped even if the insulatingfilms 4D having the aforementioned thickness are prepared by the siliconwafer process, because the films 4D are formed only partially.

On the other hand, FIGS. 26 to 28 present various patterns of theinsulating films 4D to be formed in the portions of the principalsurface of the semiconductor chip 1, to which at least the leading endsof the signal inner leads 3A₁ and the common inner leads 3A₂, and thesuspending leads are to be adhered.

As is now apparent from the foregoing description, according to thepresent Embodiment III, the whole region of the principal surface of thesemiconductor chip 1 except the bonding pads (or external terminals) BPis coated with the alpha ray shielding polyimide film 8, and theprincipal surface of the semiconductor chip 1 is formed with theinsulating films 4D at the portions to which at least the leading endsof the signal inner leads 3A₁ and the common inner leads 3A₂ are to beadhered. As a result, the whole region of the circuit can be shieldedfrom the alpha ray shielding polyimide film 8, and the semiconductorchip 1 can be fixedly adhered by the insulating films 4D.

Since, moreover, the insulating films 4D are formed at the portions onthe principal surface of the semiconductor chip 1, to which at least theleading ends of the inner leads 3A and the suspending leads 3C areadhered, it is possible to reduce the stray capacity between thesemiconductor chip 1 and the inner leads 3A.

Since, furthermore, the insulating films 4D are made of the thermosetresin containing the printable inorganic filler, they can be formedhighly accurately during the wafer process.

Since, furthermore, the semiconductor chip 1 and the resin areexcellently adhered by forming the polyimide film 9 on the side of thesemiconductor chip 1 opposite to the principal surface, it is possibleto prevent the package cracking.

Furthermore the insulating films 4D are formed highly accurately by thebatch wafer process including the steps of: adhering the solvent-peelingtype dry film A to the silicon wafer 10; applying the pasty insulator(or printing paste) after the ordinary exposing and developing Steps;burying it with the squeeze; heating and curing it; and peeling thesolvent-peeling type dry film. Thus, it is possible to improve theproductivity.

Since, furthermore, the insulating films 4D are formed only by exposingand developing the solder resist dry film D, the productivity can befurther improved.

Embodiment IV

The resin-sealed type semiconductor device according to the EmbodimentIV of the present invention is constructed, as shown in FIG. 29(presenting a perspective view in partial section): such that the signalinner leads 3A₁ and the common inner leads 3A₂ are adhered to theprincipal surface of the semiconductor chip 1 of the foregoingEmbodiment I through the insulating films 4 for insulating themelectrically from the semiconductor chip 1; and such that the signalinner leads 3A₁, the common inner leads 3A₂ and the semiconductor chip 1are electrically connected through the bonding wires 5 and sealed with amold resin 2A. The semiconductor device is further constructed, as shownin FIG. 30 (presenting a section taken along line V--V of FIG. 29 andshowing the state before molded with a resin), such that the principalsurface of the semiconductor chip 1 is so partially covered with asubstance 20, which is more flexible or fluid than the mold resin, as toshield all over the bonding wires 5, and such that the substance 20 issealed up at its outer side with the resin 2A.

More specifically, there is provided a dam 21 for covering all over thebonding wires 5 extending across the common inner leads 3A₂ with theflexible/fluid substance 20. This substance 20 may be made of fluidsilicone gel, for example, and is dropped and set on the bonding wires 5until it is sealed with the resin by the transfer mold.

The dam 21 is made of silicone rubber containing a highly viscous silicafiller.

On the other hand, the aforementioned flexible/fluid substance 20 neednot always be the above-specified gel but may be exemplified by variousmaterials such as silicone grease or rubber if it has such a flexibilityor fluidicity as to deform the bonding wires 5 therein. Thus, thebonding wires 5 can freely follow the deformations, even if theprincipal surface of the semiconductor chip 1 is peeled to expand thesteam when the package having absorbed moisture is to be subjected tothe reflow soldering treatment, so that they can be prevented from beingbroken.

Moreover, the bonding wires 5 are suppressed from being deformed duringthe transfer molding of the mold resin 2A. Even if the wires 5 areextended to run across the common inner leads 3A₂, the bonding wires 5can be prevented from being deformed during the molding, from beingshorted to each other or from contacting with the common inner leads3A₂.

On the other hand, the substance covering the bonding wires 5 need notbe the flexible/fluid substance if it is used with a view to preventingthe deformations of the bonding wires 5. The substance may beexemplified by an epoxy resin having a modulus of elasticity as high asthat of the outer resin 2A transfer-molded, if it can pot the bondingwires 5 over the principal surface of the semiconductor chip 1.

In case the flexible/fluid substance 20 has a fluidicity, its viscosityhas to be higher than the molten viscosity of the resin 2A in thetransfer mold.

Since, moreover, the resin 2A is kept away from direct contact with thebonding wires 5 by the flexible/fluid substance 20, the bonding wires 5are prevented from being repeatedly deformed in the temperature cycle bythe relative thermal deformations between the semiconductor chip 1 andthe mold resin 2A so that they are not broken by the fatigue.

In case the flexible/fluid substance 20 is used, the bonding pads BP areprevented from having their surfaces gapped by the thermal stress sothat their aluiminum can be prevented from being corroded by themoisture.

FIG. 31 is a section showing the state before the resin mold showing theresin-sealed type semiconductor device according to another embodimentin case the flexible/fluid substance 20 is used.

Since the interfaces between the signal inner leads 3A₁ and the resin 2Aare more reluctant to be gapped than the principal surface of thesemiconductor chip 1, as shown in FIG. 31, the bonding portions of thebonding wires 5 at the side of the signal inner leads 3A₁ are lessbroken. According to this embodiment, therefore, only the (first)bonding portions liable to be broken at the semiconductor chip 1 areformed with the flexible/fluid substance 20. As a result, a breakpreventing effect can be attained to some extent if the bonding wires 5can be freely deformed.

Moreover this embodiment makes use of the common inner leads 3A₂ inplace of the foregoing dam 21 of FIG. 30.

Since, in the case of this embodiment, all the bonding wires 5 are notcovered with the flexible/fluid substance 20, they are subjected torepeated deformations by the relative thermal deformations between thesemiconductor chip 1 and the mold resin 2A, in case the package is heldin the temperature cycle, so that they are more liable to be broken dueto fatigue than those of the embodiment of FIG. 30.

Since, moreover, the flexible/fluid substance 20 can be made less andlower, it is possible not only to prevent the disconnections during thereflow soldering operations and the wire deformations during thetransfer mold but also to thin the package as a whole thereby to improvethe packing density. FIG. 32 is a section showing the state before theresin mold of the resin-sealed type semiconductor device according toanother embodiment of the present invention in case the flexible/fluidsubstance 20 is used.

According to this embodiment, as shown in FIG. 32, all the bonding wires5 are covered to shield all over the principal surface of thesemiconductor chip 1 with the flexible/fluid substance 20.

Effects similar to those of the foregoing embodiment of FIG. 30 can beattained, and the whole region of the principal surface of thesemiconductor chip 1 is covered with the flexible/fluid substance 20 sothat the moisture resistance can be better improved.

Since, however, the flexible/fluid substance 20 has a large surfacearea, the interfaces with the mold resin 2A are gapped during the reflowsoldering operation so that the upper mold resin 2A is liable to becracked when it is exposed to a vapor pressure.

FIG. 33 is a section showing the state before the resin mold of theresin-sealed type semiconductor device of another embodiment in case theflexible/fluid substance 20 is used.

According to this embodiment, as shown in FIG. 33, all the bonding wires5 mounted over the principal surface of the semiconductor chip 1 arecovered with the substance 20 which is more flexible or fluid than themold resin 2A.

The flexible/fluid substance 20 covering the bonding wires 5 need not beshaded to rise on the principal surface of The semiconductor chip 1 butmay be applied to only the surfaces of the bonding wires 5.

In order to effect such coverage, the flexible/fluid substance 20 isfirst diluted to a low viscosity with a solvent and is then dropped tothe semiconductor chip 1 to cover the bonding wires 5. After this, thesolvent is evaporated to make the coverage.

In this case, the thicker layer of the flexible/fluid substance over thesurfaces of the bonding wires 5 has the better effects for preventingthe disconnections and the deformations of the bonding wires 5.

Thanks to this structure, the amount of the flexible/fluid substance 20for attaining the effects similar to those of the foregoing embodimentshown in FIG. 30 can be reduced to prevent the package crack which mightotherwise be caused by the vapor pressure between the flexible/fluidsubstance 20 and the mold resin 2A.

FIG. 34 is a section before the resin mold of the resin-sealed typesemiconductor device according to another embodiment in case theflexible/fluid substance 20 is used.

According to this embodiment, as shown in FIG. 34, the bonding wires 5are covered with the flexible/fluid substance 20, and the mold resin 2Aat the side opposite to the principal surface of the semiconductor chip1 is bored with a hole 22 to expose a portion of the semiconductor chip1 substantially to the outside.

Here, the word "substantially" imagines the inevitable existence ofeither a thin cover film of the mold resin 2A at the side opposite tothe principal surface of the semiconductor chip or such a thin resinlayer as will be easily broken in case the steam pressure is establishedin the package 2.

Since the moisture resistance of the bonding pads BP can be retained bythe flexible/fluid substance 20 without breaking the bonding wires 5 inthe temperature cycle when in the reflow soldering operations, it is notdegraded even if the hole 22 is formed in the portion of the mold resin2A.

Since, moreover, the steam generated in the package during the reflowsoldering operation is released through the hole 22 to the outside, thepressure is not built up to prevent the resin cracking.

Furthermore, the side of the hole opposite to the principal surface ofthe semiconductor chip 1 need not be completely exposed but may beclogged with the mold resin 2A if this resin 2A can be easily cleared bythe vapor pressure.

As is now apparent from the description thus far made, according to theembodiment IV, the bonding wires 5 can be prevented from being broken,even if the principal surface of the semiconductor chip 1 is peeled toexpand the steam during the reflow soldering operation.

It is also possible to prevent the bonding wires 5 from being shortedduring the transfer mold or from contacting with the common inner leads3A₂.

The resin cracking during the reflow soldering operation can beprevented without degrading the moisture resistance of the bonding padsBP and causing the disconnections of the bonding wires 5 in thetemperature cycle.

Embodiment V

The resin-sealed type semiconductor device according to the Embodiment Vof the present invention is modified from the resin-sealed typesemiconductor device of the foregoing Embodiment I such that the side ofthe semiconductor chip 1 opposite to the principal surface is recessedor raised at 101, i.e., formed with a round recess, as shown in FIG. 35(presenting a section).

The mold resin 2A is restrained on the semiconductor chip 1 by thatrecess 101 so that the reflow cracking can be prevented by reducing thestress which is to be established in the mold resin portions of thecorners of the side of the semiconductor chip 1 opposed to the principalsurface.

Here, the recess 101 may be formed by the etching or another method.

FIG. 36A (presenting a top plan view taken from the side opposite to theprincipal surface of FIG. 3) and FIG. 36B (presenting section taken onthe transverse center line of FIG. 36A) show a modification of therecess 101 which is formed in the side opposite to the principal surfaceof the semiconductor chip 1. In this modification, an annular recess101a is formed in the side opposite to the principal surface of thesemiconductor chip 1.

FIG. 37A (presenting a top plan view) and FIG. 37B (presenting asection) show another modification of the recess 101 which is formed inthe side opposite to the principal surface of the semiconductor chip 1.In this modification, a square recess 101b is formed in the sideopposite to the principal surface of the semiconductor chip 1.

FIG. 38A (presenting a top plan view) and FIG. 38B (presenting a sideelevation) show another modification of the recess 101 which is formedin the side opposite to the principal surface of the semiconductorchip 1. In this modification, a round rise 101c is formed in the sideopposite to the principal surface of the semiconductor chip 1.

FIG. 39A (presenting a top plan view) and FIG. 39B (presenting a sideelevation) show another modification of the recess 101 which is formedin the side opposite to the principal surface of the semiconductorchip 1. In this modification, a square rise 101d is formed in the sideopposite to the principal surface of the semiconductor chip 1.

FIG. 40A (presenting a top plan view) and FIG. 40B (presenting a sideelevation) show another modification of the recess 101 which is formedin the side opposite to the principal surface of the semiconductorchip 1. In this modification, an elliptical recess 101e is formed in theside opposite to the principal surface of the semiconductor chip 1.

FIG. 41A (presenting a top plan view ) and FIG. 41B (presenting a sideelevation) show another modification of the recess or rise 101 which isformed in the side opposite to the principal surface of thesemiconductor chip 1. In this modification, recesses or rises 101f areformed in the groove shape in the side opposite to the principal surfaceof the semiconductor chip 1. The grooves may take in the form of alattice.

Since one of the recesses or rises 101a to 101f is formed in the sideopposite to the principal surface of the semiconductor chip 1, as hasbeen described above, the semiconductor chip 1 can be firmly restrictedby the mold resin 2A.

It is also possible to reduce the stress which is generated in the moldresin 2A by the corner portions at the side opposite to the principalsurface of the semiconductor chip 1.

FIG. 42 shows another embodiment according to the present invention andbelonging to the Embodiment V. The aforementioned recess or rise 101 isformed in the side opposite to the principal surface of thesemiconductor chip 1 while leaving an silicon oxide film 102 on the sideopposite to the principal surface of the semiconductor chip 1 of theEmbodiment V.

Since the silicon oxide film 102 is thus left on the side opposite tothe principal surface of the semiconductor chip 1, the adhesion betweenthe silicon oxide film 102 and the mold resin 2A is so strong that themold resin 2A can be prevented from being peeled off from the sideopposite to the principal surface of the semiconductor chip 1.

Thanks to the recess or rise 101, moreover, the semiconductor chip 1 canbe firmly restricted by the mold resin 2A.

Embodiment VI

The resin-sealed type semiconductor device according to the EmbodimentVI of the present invention is constructed, as shown in FIG. 43(presenting a perspective view in partial section ) and FIG. 44(presenting a section taken along line VI--VI of FIG. 43): such than thesignal inner leads 3A₁ and the common inner leads 3A₂ are adhered to theprincipal surface of the semiconductor chip 1 of the foregoingEmbodiment I through the insulating films 4 for insulating themelectrically from the semiconductor chip 1; and such that the spiralinner leads 3A₁, the common inner leads 3A₂ and the semiconductor chip 1are electrically connected through the bonding wires 5 and sealed with amold resin 2A. The semiconductor device is equipped at the longitudinalcenters of the sides of the package 2 with radiating leads 301a whichare insulated from the semiconductor chip 1 and which have theirone-side ends extended to above the exothermic portions of the principalsurface of the semiconductor chip 1 and their other ends extended tobelow the outside of the side of the package 2 opposite to the principalsurface of the semiconductor chip 1.

Thus, the one-side ends of the radiating leads 301a electricallyinsulated from the semiconductor chip 1 are extended at the longitudinalcenters of the sides of the package to above the exothermic portions ofthe principal surface of the semiconductor chip 1, and the other ends ofthe radiating leads 301a are extended to below the outside of thepackage 2 opposite to the principal surface of the semiconductor chip 1,so that the radiation efficiency of the exothermic portions of thesemiconductor chip 1 can be improved.

FIGS. 45 (presenting a perspective view in partial section) and FIG. 46(presenting a section taken along line VII--VII of FIG. 45) show amodification of the radiating leads 301a shown in FIG. 43. The modifiedradiating leads 301b have their one-side ends extended to above theexothermic portions of the principal surface of the semiconductor chip 1and their other ends extended to above the outside of the package 2 atthe side of the principal surface of the semiconductor chip 1.

The radiating leads 301b have their extensions providing the radiatingplates.

Thus, at the longitudinal centers of the sides of the package, theone-side ends of the radiating leads 301b electrically insulatedsemiconductor chip 1 are extended to above the exothermic portions ofthe principal surface of the semiconductor chip1, and the other ends ofthe radiating leads 301b are extended to above the outside of thepackage 2 at the side of the principal surface of the semiconductor chip1, so that radiating efficiency of the exothermic portions of thesemiconductor chip 1 can be improved.

Here, the other ends of the radiating leads 301b extended to above theoutside of the package 2 at the side of the principal surface of thesemiconductor chip 1 may be folded to have their volumes reduced, asindicated by broken lines in FIG. 46.

On the other hand, the lead frames for the aforementioned radiatingleads 301a and 301b are fabricated integrally with the signal leadframe.

FIG. 47 (presenting a perspective view in partial section) and FIG. 48(presenting a section taken along line VIII--VIII of FIG. 48) show amodification of the Embodiment VI shown in FIG. 39. In thismodification, radiating leads 301c have their one-side ends extended tothe sides opposite to the exothermic portions of the principal surfaceof the semiconductor chip 1 and their other ends extended to below theoutside of the package 2 opposite to the principal surface of thesemiconductor chip 1.

Thus, at the longitudinal centers of the sides of the package, theone-side ends of the radiating leads 301c electrically insulated fromthe semiconductor chip 1 are extended to the sides opposite to theexothermic portions of the principal surface of the semiconductor chip1, and the other ends of the radiating leads 301c are extended to belowthe outside of the package 2 opposite to the principal surface of thesemiconductor chip 1, so that the radiating efficiency of the exothermicportions of the semiconductor chip 1 can be improved.

The one-side ends of the radiating leads 301c need not always beelectrically insulated from the semiconductor chip 1 by means of theinsulating film.

In this-case, moreover, the lead frame of the radiating leads 301c isfabricated separately of the signal lead frame.

Embodiment VIII

The resin-sealed type semiconductor device according to the EmbodimentVII of the present invention is constructed, as shown in FIG. 49(presenting a perspective view in partial section) and FIG. 50(presenting a section taken along line IX--IX of FIG. 49): such that thesignal inner leads 3A₁ and the common inner leads 3A₂ are adhered to theprincipal surface of the semiconductor chip 1 of the foregoingEmbodiment I shown in FIG. 1 through the insulating films 4 forinsulating them electrically from the semiconductor chip 1; and suchthat the signal inner leads 3A₁, the common inner leads 3A₂ and thesemiconductor chip 1 are electrically connected through the bondingwires 5 and sealed with a resin. In this semiconductor device, theprincipal surface of the semiconductor chip 1 is arranged with thebonding pads BP which do not intersect the bonding wires 5 and thecommon inner leads 3A₂ arranged on the principal surface.

The element layout and bonding pads BP of the semiconductor chip 1 ofthe present Embodiment VII are shown in FIG. 51 (presenting a layout topplan view).

Specifically, the memory array (MA) is arranged substantially all overthe area of the DRAM 1. In this DRAM 1 of the present embodiment VII,the memory cell array is coarsely divided into eight memory cell arrays11A to 11H, although not limitative thereto. As shown in FIG. 51, thefour memory cell arrays 11A, 11B, 11C and 11D are arranged at the upperside of the DRAM 1, and the four memory cell arrays 11E, 11F, 11G and11H are arranged at the lower side. Each of these eight memory cellarrays 11A to 11H is further finely divided into sixteen memory cellarrays (MA) 11. In short, the DRAM 1 is arranged with one hundred andtwenty eight memory cell arrays 11E. Each of the 128 memory cell arrays11 has a capacity of 128 [Kbits].

The sense amplifier (SA) 13 is interposed between the two of the 128memory cell arrays 11 of the DRAM1. The sense amplifier 13 isconstructed of a complementary MOSFET (CMOS). The column address decoder(YDEC) 12 is arranged at one lower end of each of the four 11A, 11B, 11Cand 11D of the eight memory cell arrays of the DRAM 1. Likewise, thecolumn address decoder (YDEC) 12 is arranged at one upper end of each ofthe memory cell arrays 11E, 11F, 11G and 11H.

The peripheral circuit 17 and the external terminals BP are interposedbetween the two 11A and 11B, the two 11C and 11D, the two 11E and 11F,and the two 11G and 11H of the eight memory cell arrays of the DRAM 1.On the other hand, the peripheral circuits 17 and the peripheralcircuits 18 are disposed at the individual lower regions of the memorycell arrays 11A, 11B, 11C and 11D and at the individual upper regions ofthe memory cell arrays 11E, 11F, 11G and 11H. The peripheral circuits 17are exemplified by a main amplifier, an output buffer circuit, asubstrate potential generator (or V_(BB) generator) and a power sourcecircuit.

The peripheral circuit 18 is further exemplified by a row address strobe(RAS) circuit, a write enable (WE) circuit, a data input buffer, aV_(CC) limitter, an X-address driver (i.e., logical stage), anX-redundancy circuit, an X-address buffer, a column address strobe (CAS)circuit, a test circuit, a VDL limitter, a Y-address driver (i.e.,logical stage), a Y-redundancy circuit, a Y-address buffer, a Y-addressdriver (i.e., drive stage), an X-address driver (i.e., drive stage), anda mat selecting signal circuit (i.e., drive stage) (as should bereferred to FIG. 4 and its description).

Since the aforementioned resin-sealed type semiconductor device 2 isconstructed to have the LOC structure and since the inner leads 3A areextended to the central portion of the DRAM 1, the external terminals BPare arranged at the central portion of the DRAM 1 and on the principalsurface of the semiconductor chip 1 such that they are kept away fromintersecting the bonding wires 5 and the common inner leads 3A₂ arrangedon the principal surface of the semiconductor chip 1.

The external terminals BP are arranged within the regions defined by thememory cell arrays 11A, 11B, 11C, 11D, 11E, 11F, 11G and 11H from theupper to the lower ends of the DRAM 1. The signals to be applied to theexternal terminals BP will not be described here because they have beendescribed in connection with the resin-sealed type semiconductor device2 shown in FIG. 1.

Since the inner leads 3A supplied with the reference voltage (V_(SS) ;and the power source voltage (V_(CC)) are extended from the upper to thelower ends of the surface of the DRAM 1, the DRAM 1 is arranged with theplural external terminals BP for the reference voltage (V_(SS)) and thepower source voltage (V_(CC)) in the extending direction. In short, theDRAM 1 is constructed to effect sufficient supply of the referencevoltage (V_(SS)) and the power source voltage (V_(CC)).

As has been described above, according to the present Embodiment VII,the principal surface of the semiconductor chip 1 is arranged with thebonding pads BP which do not intersect with the bonding wires 5 and thecommon inner leads 3A₂ arranged on the same surface. Thus, it ispossible to prevent the shorting between the bonding wires 5 forconnecting the signal inner leads 3A₁ and the semiconductor chip 1 andthe common inner leads 3A₂.

Next, the lead frame will be described in detail in the following.

As shown in FIG. 52 (presenting an overall top plan view of the leadframe), the lead frame 3 of the present Embodiment VII is equipped withtwenty signal inner leads 3A₁ and two common inner leads 3A₂. The innerleads 3A₁ are stepped, as shown in FIG. 50 (presenting a section), suchthat the gap between their portions nearer the outer leads 3B than theirportions contacting with the insulating films 4 and the semiconductorchip is larger than the gap between their portions contacting with theinsulating films (or insulators) 4 and the semiconductor chip 1. By thusadopting the stepped structure in the semiconductor chip 1, the straycapacity between the semiconductor chip 1 and the signal inner leads 3A₁can be reduced to a lower level than that of the prior art to improvethe signal transmission rate and to drop the electrical noises.

The present Embodiment VII is identical to the foregoing Embodiment Iexcept the arrangement of the bonding pads BP on the principal surfaceof the semiconductor chip 1 and the lead frame.

Incidentally, the techniques of the foregoing Embodiments II-VI cannaturally be applied to the present Embodiment VII.

Embodiment VIII

The resin-sealed type semiconductor device according to the EmbodimentVIII of the present invention is, as shown in FIG. 53 (plan presentingthe schematic mechanism of the lead frame in Embodiment VIII) amodification of the lead frame of the foregoing Embodiment I, in whichinner leads 3C₁ (suspending leads) to be supplied with no power arefolded to fix the side of the semiconductor chip 1 opposite to theprincipal surface.

As shown in FIG. 54A (presenting a section showing the semiconductorchip fixing portion) and FIG. 56 (presenting a section showing thesignal inner leads and the common inner leads before the resin molding),moreover, the semiconductor chip 1 is adhered and fixed with theadhesive 7 by the suspending leads 3C₁ such that the signal inner leads3A₁ and the common inner leads 3A₂ are arranged in floating states fromthe principal surface of the semiconductor chip 1.

The adhesive 7 may be any of the aforementioned adhesives such as epoxyresins or resol resins.

On the other hand, the adhesions may be effected through the insulatingfilms 4 between the suspending leads 3C₁ and the semiconductor chip 1.

In this case, the connections of the signal inner leads 3A₁ and thecommon inner leads 3A₂ and the bonding pads BP of the semiconductor chip1 by means of the bonding wires 5 are accomplished by holding the signalinner leads 3A₁ and the common inner leads 3A₂ on the semiconductor chip1 by means of a jig. If the holding jig is removed after the wirebondings, the signal inner leads 3A₁ and the common inner leads 3A₂ arebrought into the state shown in FIG. 56 by the spring-back effect of thesuspending leads 3C₁.

As shown in FIG. 54B, on the other hand, the signal inner leads 3A₁ andthe common inner leads 3A₂ may be arranged in a floating state from theprincipal surface of the semiconductor chip 1 (as shown in FIG. 56) bysandwiching the insulating films 4 of a predetermined thickness betweenthe suspending leads 3C of the lead frame 2 applied to the foregoingEmbodiment 1 and the principal surface of the semiconductor chip 1 andadhering them by means of the adhesive 7. In this case, the insulatingfilms 4 ordinarily have a thickness of 150 microns but can have a largerthickness.

As shown in FIG. 55 (presenting a section showing the state before theresin molding), on the other hand, insulating plates 40 may besandwiched between the signal inner leads 3A₁ and the common inner leads3A₂ and the principal surface of the semiconductor chip 1 to connect thesignal inner leads 3A₁, the common inner leads 3A₂ and the semiconductorchip 1 electrically by the bonding wires 5 and to seal them up with themold resin.

As shown in FIG. 57 (presenting a section showing the state before theresin molding), moreover, the insulating plate 40 may be sandwiched onlybetween the one-side, e.g., lefthand signal inner lead 3A₁ and commoninner lead 3A₂ and the semiconductor chip 1, whereas the righthandsignal inner lead 3A₁ and common inner lead 3A₂ and the semiconductorchip 1 may be electrically connected through the bonding wires 5 andsealed with the mold resin such that the signal inner lead 3A₁ and thecommon inner lead 3A₂ are floating from the principal surface of thesemiconductor chip 1.

In order that the signal inner leads 3A₁ and the common inner leads 3A₂may be arranged in a floating state from the principal surface of thesemiconductor chip 1 (as shown in FIG. 56), as shown in FIG. 54C, thesuspending leads 3C₁ may be deeply folded to form suspending leads 3C₂for fixedly adhering the side of the semiconductor chip 1 opposite tothe principal surface. As a result, the side of the semiconductor chip 1opposite to the principal surface is adhered and fixed by the suspensionleads 3C₂ so that the signal inner leads 3A₁ and the common inner leads3A₂ are floating from the principal surface of the semiconductor chip 1,thus eliminating the step of adhering the insulating films 4. Moreover,the semiconductor chip 1 is firmly fixed. Since no lead line is adheredto the memory cells, it is possible to reduce the breakage of the memorycells.

As has been described above, according to the present Embodiment VIII,the moisture absorption can be reduced by eliminating or minimizing theuse of the insulating films 4 to make the solder reflow resistanceadvantageous.

In the Embodiment VIII, it is preferable to apply the alpha rayshielding polyimide film to the whole region of the principal surface ofthe semiconductor chip 1 except the bonding pads.

Embodiment IX

in the resin-sealed type semiconductor device according to theEmbodiment IX of the present invention, as shown in FIGS. 58 and 59(presenting layouts of the semiconductor chip), there are provided twosemiconductor chips 1A and 1B which are formed in a mirror symmetry withthe bonding pads BP (or solder bumps) connected with the inner leads.

In FIG. 58, the CAS0 terminals (i.e., bonding pads BP) and the CAS1terminals (i.e., bonding pads BP) are shared, and the other terminals(i.e., bonding pads BP) are held in common. This layout doubles thecapacity in the word direction.

In FIG. 59, the Do terminals and the Di terminals are shared, whereasthe other terminals are held in common. This layout doubles the capacityin the bit direction.

As shown in FIG. 60 (presenting a section for explaining the package)moreover at the sides of the individual principal surfaces of the twosemiconductor chips 1A and 1B and across the inner leads 3A, these innerleads 3A and the bonding pads BP of the semiconductor chip 1 areelectrically connected through the solder bumps 5C and sealed up withthe mold resin.

Thus, in the two semiconductor chips 1A and 1B formed in the mirrorsymmetry with the inner leads 3A and the bonding pads BP, the innerleads 3A and the bonding pads BP of the semiconductor chip 1 areelectrically connected at the sides of the individual principal surfacesand across the inner leads 3A through the solder bumps 5C and sealed upwith the mold resin so that an element having a twice capacity can bepackaged without changing the contour of the package 2.

Embodiment X

In the resin-sealed type semiconductor device according to theEmbodiment X of the present invention, as shown in FIG. 61 (presenting aperspective view taken from the side opposed to the wiring substrate ofthe resin-sealed type semiconductor device of the Embodiment X) and FIG.62 (presenting a section taken along line XI--XI of FIG. 61), thepackage 2 of the semiconductor device of the foregoing Embodiment I isformed, at its side facing the substrate, with a radiating groove 50which is opened to the outside. In this case, the distance between thebottom 50A of the radiating groove 50 and the semiconductor chip 1,i.e., the thickness of the mold resin 2A below the semiconductor chip 1is set at 0.3 mm or less.

By forming the radiating groove 50, as shown in FIGS. 68 and 69(presenting sections showing the state in which the resin-sealed typesemiconductor device of the Embodiment X is packed in the wiringsubstrate), the gap 51D between a substrate 51A or 51B and the bottom50A of the radiating groove 50 is so enlarged that it is supplied withthe cooling air, if directed normal to the drawing surface, whereby theradiation is effected from the bottom 50A of the radiating groove 50,too, to reduce the heat resistance of the semiconductor device.

Incidentally, in the structure of the present embodiment, the mold resin2A below the semiconductor chip 1 is thinned to make it necessary tomake a device when in the resin molding operation. If the mold resin 2Ahaving a low molten viscosity in the molding operation, the package 2can be formed, as shown in FIG. 61.

Next, a modification of the resin-sealed type semiconductor device ofthe foregoing Embodiment X is shown in FIG. 63 (presenting a section).

In this modified semiconductor device, as shown in FIG. 63, the uppersurface of the package 2 shown in FIG. 61 is also formed with an openradiating groove 53. The distance between the bottom 50A of theradiating groove 50 and the bottom 53A of the radiating groove 53, i.e.,the thickness of the mold resin below and above the semiconductor chip 1is set at 0.3 mm or less.

By thus thinning the mold resin 2A of the package 2 above thesemiconductor chip 1, the heat transfer surface is increased, but theheat resistance of the semiconductor device is decreased, so that thewhole heat resistance can be accordingly reduced. As shown in FIG. 69,moreover, the gap when the semiconductor device is mounted on thesubstrates 51A and 51B can be shortened by twice as large as the depthof the groove so that the packing density can be increased.

Another modification of the semiconductor device according to theEmbodiment X is shown in FIG. 64 or 65.

In this modified semiconductor device, as shown in FIG. 64 or 65, themold resin 2A of the package of FIG. 62 or 63 below the semiconductorchip 1 is removed to expose the side of the semiconductor chip 1, whichis opposed to the principal surface, to the outside.

Thus, the mold resin 2A the package 2 below the semiconductor chip 1 isremoved to expose the side opposite to the principal surface of thesemiconductor chip 1 to the outside so that the heat resistance of thesemiconductor device can be dropped to reduce the overall heatresistance accordingly.

Thus, it is possible to prevent the cracking from the corner portions ofthe semiconductor chip 1 due the temperature cycle.

Another modification of the semiconductor device of the Embodiment X isshown in FIG. 66 or 67.

In this modified semiconductor device, as shown in FIG. 66 or 67, therelation between the semiconductor chip 1 and the output leads 3B isreversed in the semiconductor device in which the mold resin 2A of thepackage 2 shown in FIGS. 62 and 64 below the semiconductor chip 1 isremoved to expose the side of the semiconductor chip 1 opposite to theprincipal surface to the outside.

Thus, the cooling efficiency can be improved in case the cooling of theupper surface of the packing substrate 51 is dominant.

In the modification shown in FIG. 66 or 67, the the package 2 is furtherformed with the radiating groove at the side of the substrate.

Next, one embodiment of a method of packing the substrate of theresin-sealed type semiconductor device of the present invention shown inFIGS. 61 to 67 will be described in the following.

In the embodiment of the method of packing the substrate of theresin-sealed type semiconductor device shown in FIGS. 61 to 67, as shownin FIG. 68, the resin-sealed type semiconductor devices 60A to 60H shownin FIGS. 61 are planarly packed on the respective two sides of thesubstrates 51A and 51B by means of solder 61.

By thus packing the resin-sealed type semiconductor devices 60A to 60Hon the substrates 51A and 51B, it is possible to improve the packingdensity of the semiconductor device and to radiate from the substrates51A and 51B of the package 2, too. More specifically since theradiations of the resin-sealed type semiconductor devices 60A to 60H areeffected through the gap 51D between each of their packages 2 and thesubstrate 51A or 51B packing the former, the resistance to the coolingdraft can be reduced to improve the radiating efficiency.

As shown in FIG. 69, the radiating groove 53 and the rise 54 above thepackage 2 of the resin-sealed Type semiconductor device of theembodiment shown in FIG. 63 are packed together between the twosubstrates 51A and 51B.

Since the resin-sealed type semiconductor device is thus packed, itspacking density can be further improved. The radiations can also beaccomplished from the side of the substrate 51A or 51B of the package 2.Specifically, the gap when the resin-sealed type semiconductor device isplaced over the substrate 51A or 51B can be shortened to one half of thedepth of the groove, the packing density can be increased (to 1.5 timesas high as that of the embodiment of FIG. 64).

Since, moreover, the radiations of the resin-sealed type semiconductordevice are accomplished through the gap 51D between the package 2 andits packing substrate 51A or 51B, the resistance to the cooling draftcan be reduced to improve the radiating efficiency.

Embodiment XI

The resin-sealed type semiconductor device for sealing the DRAMaccording to the Embodiment XI of the present invention is shown in FIG.70 (presenting a perspective view showing the exterior) and FIG. 71(presenting a partially sectional view of FIG. 70).

As shown in FIG. 70 and 71, the DRAM (or semiconductor chip) 1 is sealedup with the ZIP (Zigzag In-line Package) Type resin-sealed package 2.The DRAM 1 is constructed to have a large capacity of 16 [Mbits]×1 [bit]and a rectangular shape of 16.48 [mm]×8.54 [mm]. This DRAM 1 is sealedin the resin-sealed type package 2 of 450 [mil].

The DRAM 1 has its principal surface arranged mainly with a memory cellarray and a peripheral circuit, as shown in FIG. 71. The memory cellarray is arranged in a matrix form with memory cells (or elements) forstoring information of 1 [bit], as will be described later in detail.The peripheral circuit is composed of a direct peripheral circuit and anindirect peripheral circuit. The direct peripheral circuit is one fordirectly controlling the information writing operations and theinformation reading operations of the memory cells. The directperipheral circuit is exemplified by a row address decoder, a columnaddress decoder or a sense amplifier. The indirect peripheral circuit isone for controlling the operations of the direct peripheral circuitindirectly. The indirect peripheral circuit is exemplified by a clocksignal generator or a buffer.

The principal surface of the DRAM 1, i.e., the surface arranged with thememory cell array and the peripheral circuit is further arranged withthe inner leads 3A. The insulating films 4 are sandwiched between theDRAM 1 and the inner leads 3A. The insulating films 4 are made of apolyimide resin, for example. The surfaces of the insulating films 4 atthe individual sides of the DRAM 1 and the inner leads 3A are formedwith adhesive layers. These adhesive layers are made of a polyesteramide-imide resin or an epoxy resin. The package 2 of this kind adoptsthe LOC (Lead On Chip) structure in which the inner leads 3A arearranged over the DRAM 1. Since the package 2 adopting the LOC structurecan handle the inner leads 3A freely without being restricted by theshape of the DRAM 1, it can seal the DRAM 1 having a size enlargedaccording to the free handling. In other words, the package 2 adoptingthe LOC structure can have its packing density increased because thesealing (or package) size can be suppressed to a small value even if thesize of the DRAM 1 is enlarged with the large capacity.

The aforementioned inner leads 3A have their one-side ends made integralwith the outer leads 3B. These outer leads 3B are regulated with signalsto be applied and are numbered according to the standards. In FIGS. 70and 71, The upper Step is equipped sequentially from its left withterminals of odd numbers, e.g., 1st, 3rd, 5th, - - - , 21st and 23rd,and the lower step is equipped sequentially from its left with terminalsof even numbers, e.g., 2nd, 4th, 6th, - - - , 22nd and 24th. In short,this package 2 is composed of totally twenty four terminals, i.e., thetwelve terminals at each of the upper and lower steps.

The 1st one is an address signal terminal (A₉); the 2nd one is an idleterminal; the 3rd one is a column address strobe signal terminal (CAS);the 4th one is an idle terminal; the 5th one is a data output signalterminal; and the 6th one is a reference voltage V_(SS) terminal. Thisreference voltage V_(SS) is the circuit operation voltage of 0 [V], forexample. The 7th one is a power source voltage V_(CC) terminal. Thispower source voltage V_(CC) is the circuit operation voltage of 5 [V],for example.

The 8th one is a data input signal terminal (D_(in)); the 9th one is anidle terminal; the 10th one is a write enable signal terminal (WE); the11th one is a row address strobe signal terminal (RAS); the 12th one isan address signal terminal (A₁₁); and the 13th one is an address signalterminal (A₁₀). The 14th one is an address signal terminal (A₀); the15th one is an address signal terminal (A₁); the 16th one is an addresssignal terminal (A₂); the 17th one is an address signal terminal (A₃);and the 18th one is a power source voltage V_(CC) terminal. This powersource voltage V_(CC) is the circuit operation voltage of 5 [V], forexample.

The 19th one is a terminal for the reference voltage V_(SS), which isthe circuit operation voltage of 0 [V], for example.

The 20th one is an address signal terminal (A₄); the 21th one is anaddress terminal (A₅); the 22th one is an address terminal (A₆); the23th one is an address terminal (A₇); and the 24th one is an addressterminal (A₈).

The other ends of the inner leads 3A are extended across the individuallonger sides of the rectangle of the DRAM 1 to the center of the DRAM 1.The extensions of the other ends of the inner leads 3A are connectedwith the external terminals (i.e., bonding pads) BP arrayed at thecentral portion of the DRAM 1 through the bonding wires 5. These bondingwires 5 are made of aluminum (Al) but may be coated wires prepared bycoating gold (Au), copper (Cu) or another metal wires with an insulatingresin. The bonding wires 5 are bonded by the hot contact bonding methodusing ultrasonic vibrations.

Of the inner leads 3A, the inner leads (V_(CC)) 3A of the 7th and 18thterminals are made integral and extended along the center portion of theDRAM 1 in parallel with the longer sides of the same (as will be calledthe common inner leads or the bus bar inner leads). Likewise, the innerleads (V_(SS)) 3A of the 6th and 19th terminals are also made integraland extended along the center portion of the DRAM 1 in parallel with thelonger sides of the same (as will be called the common inner leads orthe bus bar inner leads). The inner leads (V_(SS)) 3A are individuallyextended in parallel in the regions which are defined by the leadingends of the other ends of the remaining inner leads 3A. Each of thoseinner leads (V_(CC)) 3A and (V_(SS)) 3A is enabled to supply the powersource voltage V_(CC) and the reference voltage V_(SS) to any positionof the principal surface of the DRAM 1. In short the package 2 isconstructed to absorb the power source noises easily thereby to speed upthe operations of the DRAM 1.

The shorter sides of the rectangle of the DRAM 1 are equipped with thechip supporting leads 3C.

Each of the inner leads 3A, the output leads 3B and the chip supportingleads 3C is cut from the lead frame and is molded. This lead frame ismade of a Fe-Ni alloy (containing 42 to 50[%] of Ni) or Cu, for example.

The DRAM 1, the bonding wires 5 the inner leads 3A and the chipsupporting leads 3C are sealed up with the resin sealing portion 6. Thisresin sealing portion 6 is is made of an epoxy resin to which are addeda phenol hardener, silicon rubber and a filler so as to reduce thestress. The silicon rubber is effective to drop the modulus ofelasticity and the thermal expansion coefficient of the epoxy resin. Thefiller is formed in spherical grains of silicon oxide and is effectiveto drop the thermal expansion coefficient.

As is apparent from the description thus far made, according to thepresent Embodiment XI, the 16MDRAM 1 of the ZIP package type is packedin the vertical form in the substrate so that its packing density can beimproved.

Although the present invention has been specifically described inconnection with the embodiments thereof, it should not be limitedthereto but can naturally be modified in various manners withoutdeparting from the gist thereof.

The effects to be obtained from the representatives of the inventiondisclosed herein will be briefly enumerated in the following:

(1) The semiconductor device is enabled to improve the reliability;

(2) The semiconductor device is enabled to improve the signaltransmission rate and reduce the electrical noises by the stray capacitybetween the semiconductor chip and the leads;

(3) The semiconductor device is enabled to improve the radiationefficiency of the heat generated;

(4) The semiconductor device is enabled to reduce the influences of theheat during the reflow;

(5) The semiconductor device is enabled to reduce the influences of theheat in the temperature cycle;

(6) The semiconductor device is enabled to prevent the molding defect;

(7) The semiconductor device is enabled to improve the productivity; and

(8) The semiconductor device is enabled to improve the moistureresistance.

Embodiment XII

FIG. 72 is a section showing a semiconductor device according to anotherembodiment of the present invention and taken along line XII--XII ofFIG. 74; FIG. 73 is a partially broken section taken along lineXIII--XIII of FIG. 74; FIG. 74 is a general top plan view showing thesemiconductor device; and FIG. 75 is a general top plan view showing thesemiconductor chip in a circuit block of the semiconductor device.

The present Embodiment XII is directed to the resin-sealed typesemiconductor device which has the DIP (Dual In-line Package) packagestructure using the tabless lead frame.

A package body 401 is made of a resin which is prepared by filling anepoxy resin with a filler such as silica (SiO₂) to have a thermalexpansion coefficient near that of silicone and which has a structurestrong against the bending and the reflow cracking.

From the longitudinal two sides of the package body 401, there areextended to the outside and folded downward a plurality of leads 402which constitute input/output pins and power source pins. These leads402 are made of Cu, for example, and have their surfaces plated with aSn-Ni alloy, for example.

To the surfaces of the leads 402 buried in the package body 401, thereare bonded through an adhesive 404 rectangular insulating films 403awhich are made of a polyimide resin, for example. The adhesive 404 ismade of a polyimide resin, for example.

The leads 402 are folded, as shown in FIG. 74, below the insulatingfilms 403a generally at a right angle in the horizontal direction suchthat their leading end portions plated with Ag, for example, extend fromthe shorter sides of the insulating films 403a to the outside.

As shown in FIGS. 72 and 73, moreover, the leads 402 are further foldedmidway downward below the insulating films 403a. To the resultant gapsbetween the leads 402 and the insulating films 403a, there are adheredsecond insulating films 403b which has a substantially equal thickness,so as to prevent the leads 402 from being deformed when in the moldingoperation. Incidentally, the insulating films 403b are made of the samepolyimide resin as that of the foregoing insulating film 403a.

To the upper surfaces of the insulating films 403a, there is bondedthrough an adhesive 406 a rectangular semiconductor chip 405 which ismade of single crystal of silicon. The adhesive 406 is made of a siliconresin, for example.

The chip 405 is constructed to have a slightly smaller area than that ofthe insulating films 403a. The chip 405 has its upper surface providingan integrated circuit forming surface, which is covered with apassivation film 407 of a polyimide resin so that it may be flattend.

The integrated circuit forming surface of the chip 405 is formed with aMOS DRAM of 4 mega bits, for example.

As shown in FIG. 75, the chip 405 is arranged at its center with amemory cell array M of the MOS DRAM of 4 mega bits and at its two sideswith peripheral circuits P. Between the shorter sides of the chip 405and the peripheral circuits P, there are arranged a plurality of bondingpads 408, which are electrically connected with the leads 402 throughwires 409 made of Au, Cu or Al.

In the resin-sealed semiconductor device, parasitic capacities areusually established between the chip 405 and the leads 402. Theseparasitic capacities will increase inversely proportionally to thedistance between the chip 405 and the leads 402 and proportionally totheir opposed areas. In the package structure in which most of the leads402 buried in the package body 401 are positioned below the chip 405,the opposed areas between the chip 405 and the leads 402 are enlarged toincrease the parasitic capacities.

In the present Embodiment XII, however, the leads 402 below the chip 405are folded midway downward to enlarge the distance between the chip 405and the leads 402. As a result, the parasitic capacities to beestablished between the chip 405 and the leads 402 can be reduced morethan the prior art in which the leads 402 are not folded midwaydownward.

As a result, the capacity of the leads 402 constituting the input/outputpins is reduced to speed up the access to the MOS DRAM of 4 mega bitsformed in the chip 405.

In the present Embodiment XII, the second insulating films 403b made ofthe same material as that of the insulating film 403a are adhered to thegaps between the leads 402 and the insulating film 403a. However, theinsulating films 403a and 403b may be molded in an integral manner ormade of different materials.

Embodiment XIII

FIG. 76 is a section showing a semiconductor device according to anotherembodiment of the present invention and taken along line XIV--XIV ofFIG. 77; FIG. 77 is a general top plan view showing the semiconductordevice; and FIG. 78 is a general top plan view showing the semiconductorchip of the circuit block of the semiconductor device.

The package structure of the present Embodiment XIII is the same DIP ofthe tabless lead frame type at that of the foregoing Embodiment XII.Although this Embodiment XII uses the so-called "Chip On Lead" type inwhich the leads 402 are arranged on the lower side of the chip 405, thepresent Embodiment XIII adopts the so-called Lead On Chip type in whichthe chip 405 is arranged on the lower side of the leads 402.

Specifically, the chip 405 sealed in the package body 401 made of aresin similar to that of the foregoing Embodiment XII has its uppersurface providing an integrated circuit forming surface. This integratedcircuit forming surface is formed with a MOS DRAM of 4 mega bits, forexample.

As shown in FIG. 78, the chip 405 is arranged at its central portionwith the peripheral circuit P extending in the longitudinal direction ofthe chip and at its two sides with the memory cell arrays M. Since theperipheral circuit P is arranged at the center of the chip 405, thewiring length can be made less in the longitudinal direction of the chip405 than that of the MOS DRAM of 4 mega bits of the Embodiment XII, inwhich the peripheral circuits P are arranged at the shorter sides of thechip 405, so that the wiring delay can be more reduced.

At the central portion of the chip 405, the bonding pads 408 areconcentrated between the peripheral circuit P and the memory cell arraysM.

To the upper surface of the chip 405, as shown in FIG. 76, there isbonded through the adhesive 406 the rectangular insulating film 403awhich is made of a polyimide resin, for example. This insulating film403a has a slightly larger area than that of the chip 405 and is formedat its center with an opening 410.

To the upper surface of the insulating film 403a, there are bondedthrough the adhesive 404 a plurality of leads 402. These leads 402 arefolded horizontally over the insulating film 403a, as shown in FIG. 77,to have their leading end portions arranged in the vicinity of thebonding pads 408. Moreover, the leads 402 and the bonding pads 408 areelectrically connected through the wires 409.

As shown in FIG. 76, the leads 402 are folded midway upward over theinsulating film 403a. To the resultant gaps between the leads 402 andthe insulating film 403a, there are adhered the insulating films 403bwhich have substantially the same thickness as that of the gaps.

Thus, in the present Embodiment XIII, the leads 402 over the chip 405are folded midway upward to increase the distance between the chip 405and the leads 402 accordingly. As a result, the parasitic capacity to beformed between the chip 405 and the leads 402 can be reduced more thanthe prior art in which the leads 402 are not folded midway upward.

As a result, the capacity of the leads 402 constituting the input/outputpins can be reduced to speed up the access to the MOS DRAM of 4 megabits formed on the chip 405.

Although the invention has been specifically described in connectionwith the embodiments thereof, it should not be limited to theEmbodiments XII and XIII but can naturally be modified in variousmanners within the gist thereof.

As shown in FIG. 79, for example, the present invention can be appliedto the package structure in which a predetermined integrated circuitformed on the chip 405 and the leads 402 are electrically connectedthrough solder bumps 411. In case, as shown, most of the leads 402buried in the package body 401 are arranged along the lower side of thechip 405, the parasitic capacity to be established between the leads 402and the chip 405 can be reduced by folding the intermediate portions ofthe leads 402 connecting the solder bumps 411 downward.

Although the packages of the foregoing Embodiments XII and XIII are ofthe DIP type, they should not be limited thereto but may be exemplifiedby the SOJ (Small Outline J-lead Package) or the PLCC (Plastic LeadedChip Carrier).

Moreover, the present invention should not be limited to thesemiconductor device using the tabless lead frame type but can also beapplied to the semiconductor device of the type in which the leads arearranged on the upper surface of the chip packed on the tabs.

Although the description thus far made is directed to the case in whichthe invention is applied to the MOS RAM or the background of itsapplication, the invention should not be limited thereto but can beapplied to another semiconductor memory such as an EPROM or a logicalLSI such as a microcomputer.

The effects to be attained by the representative of the inventiondisclosed herein will be briefly described in the following:

Specifically, the parasitic capacity to be established between the chipand the leads can be reduced by folding a portion of the leads, whichare arranged over or below the chip packed in the package, outward withrespect to the upper or lower sides of the chip.

Since, moreover, the insulating films are sandwiched between the chipand the leads, the distance between the chip and the leads can be sosufficiently enlarged to reduce the parasitic capacity to be establishedbetween the chip and the leads.

By arranging the peripheral circuit at the central portion of the chip,moreover, the wiring length taken in the longitudinal direction of thechip can be shortened to reduce the wiring delay.

                  TABLE 1                                                         ______________________________________                                        Resin Composition (wt. parts)                                                 ______________________________________                                        Base Resin:                                                                   Embodiment 1:                                                                 o-cresol novolak type epoxy resin:                                                                      63                                                  novolak type phenol resin:                                                                              37                                                  Embodiment 2:                                                                 resol type phenol resin:  80                                                  o-cresol novolak type epoxy resin:                                                                      20                                                  Embodiment 3:                                                                 ether type bismaleimide resin:                                                                          70                                                  epoxy acrylate resin:     30                                                  Hardening Catalyzer:                                                          Embodiment 1:             1                                                   triphenyl phosphine:                                                          Embodiment 2:             1                                                   2-phenyl-4-metyl-5-hydromethyl imidazole:                                     Embodiment 3:             0.5                                                 dicumyl peroxide:                                                             Fire Retardant:                                                               Embodiment 1:                                                                 brominated bisphenol A-type epoxy resin:                                                                10                                                  antimony trioxide:        5                                                   Embodiment 2:                                                                 Embodiment 3:                                                                 brominated visphenol A-type epoxy resin:                                                                8                                                   antimony trioxide:        2                                                   Elasticizer:                                                                  Embodiment 1:             10                                                  modified epoxy silicone:                                                      Embodiment 2:             10                                                  modified amine silicone:                                                      Embodiment 3:             10                                                  modified vinyl silicone:                                                      Filler:                                                                       Embodiment 1:             520                                                 spherical molten silica:                                                      Embodiment 2:             460                                                 spherical molten silica:                                                      Embodiment 3:             520                                                 spherical molten silica:                                                      Coupling Agent:                                                               Embodiment 1:             3                                                   epoxy silane:                                                                 Embodiment 2:             3                                                   amino silane:                                                                 Embodiment 3:             3                                                   amino silane:                                                                 Parting Agent:                                                                Embodiment 1:             1                                                   montanic ester:                                                               Embodiment 2:             1                                                   montanic ester:                                                               Embodiment 3:             1                                                   montanic ester:                                                               Coloring Agent:                                                               Embodiment 1:             1                                                   carbon black                                                                  Embodiment 2:             1                                                   carbon black                                                                  Embodiment 3:             1                                                   carbon black                                                                  Molding Properties:                                                           Molten Viscosity (p) at 180° C:                                        Embodiment 1:             215                                                 Embodiment 2:             150                                                 Embodiment 3:             200                                                 Spiral Flow (inch):                                                           Embodiment 1:             35                                                  Embodiment 2:             30                                                  Embodiment 3:             40                                                  Hot Hardness at 180° C./90s after:                                     Embodiment 1:             85                                                  Embodiment 2:             85                                                  Embodiment 3:             88                                                  Physical Properties of Set Device:                                            Glass Transition Temperature (°C.):                                    Embodiment 1:             165                                                 Embodiment 2:             220                                                 Embodiment 3:             215                                                 Linear Expansion Coefficient (10.sup.-5 /°C.):                         Embodiment 1:             1.3                                                 Embodiment 2:             1.1                                                 Embodiment 3:             1.1                                                 Bending Strength (kgf/mm.sup.2                                                in Greenhouse:                                                                Embodiment 1:             13.5                                                Embodiment 2:             14.5                                                Embodiment 3:             13.2                                                at 215° C.:                                                            Embodiment 1:             1.2                                                 Embodiment 2:             8.5                                                 Embodiment 3:             5.5                                                 Bulk Resistivity (ohms cm):                                                   in Greenhouse:                                                                Embodiment 1:             3.6 × 10.sup.16                               Embodiment 2:             1.2 × 10.sup.16                               Embodiment 3:             8.5 × 10.sup.16                               at 140° C.:                                                            Embodiment 1:             4.0 × 10.sup.14                               Embodiment 2:             8.5 × 10.sup.13                               Embodiment 3:             5.0 × 10.sup.15                               Moisture Absorption (%) at 65° C./95% RH:                              Embodiment 1:             0.8                                                 Embodiment 2:             0.8                                                 Embodiment 3:             1.0                                                 Fire Retardant (UL-94, 1.6 mm thickness):                                     Embodiment 1:             V-O                                                 Embodiment 2:             V-O                                                 Embodiment 3:             V-O                                                 Properties of Extract                                                         (120° C./after extraction of 168 h):                                   pH:                                                                           Embodiment 1:             4.0                                                 Embodiment 2:             4.2                                                 Embodiment 3:             4.0                                                 Electrical Conductivity (μs/cm):                                           Embodiment 1:             85                                                  Embodiment 2:             65                                                  Embodiment 3:             150                                                 CL.sup.-  (ppm):                                                              Embodiment 1:             3.2                                                 Embodiment 2:             <1                                                  Embodiment 3:             <1                                                  ______________________________________                                    

                                      TABLE 2                                     __________________________________________________________________________    Washing Times                                                                         0   1   2   3   4   5     6                                           Properties                                                                    of Extracts:                                                                  pH      3.0 3.3 3.4 3.4 3.5 3.5   3.6                                         Electrical                                                                            1500                                                                              350 125 50  27  20   18 (μs/cm)                                Conductivity                                                                  Ionic Impuri                                                                  ties (ppm) *1                                                                 CL.sup.-                                                                              75  15  3   <1  <1  <1  <1                                            Br.sup.-                                                                              5   <1  <1  <1  <1  <1  <1                                            Na.sup.+                                                                              30  8   2   <1  <1  <1  <1                                            K.sup.+ 15  3   <1  <1  <1  <1  <1                                            Zn.sup.+2                                                                             250 75  18  3   <1  <1  <1                                            NH.sub.4.sup.+                                                                        <1  <1  <1  <1  <1  <1  <1                                            Properties                                                                    of Resins                                                                     Softening                                                                             62  65  65  68  70  73   75                                           Temp. (°C.)                                                            Gel Time                                                                              31  37  40  42  42  43   45                                           (sec) *2                                                                      __________________________________________________________________________     In the Table 2:                                                               *1: Densities of Extracts;                                                    *2: JISK-5909 (Hot Plate).                                               

What is claimed is:
 1. A semiconductor device comprising:a rectangularsemiconductor chip having a principal surface with circuit elements anda plurality of external terminals; a plurality of leads extending oversaid principal surface, each comprising an inner lead portion and anouter lead portion, said inner lead portion including a first region, asecond region and a stepped portion between said first region and saidsecond region; a plurality of wires for electrically connecting saidexternal terminals with each of said first regions of said inner leadportions; and a sealing member for sealing said semiconductor chip, saidinner lead portions and said wires, said sealing member comprising amolding resin, wherein a distance between said second region and saidprincipal surface is larger than a distance between said first regionand said principal surface.
 2. A semiconductor device according to claim1, wherein said plurality of external terminals are arrangedsubstantially at a central area of said rectangular semiconductor chipand substantially in parallel with the longer sides of said rectangularsemiconductor chip.
 3. A semiconductor device according to claim 2,further comprising:another plurality of external terminals arrangedsubstantially in the central area of said rectangular semiconductorchip; a common lead comprising a first portion and a second portion,said first portion extending across said longer sides of saidrectangular semiconductor chip and said second portion extending alongsaid external terminals, said common lead comprising a lead to whichterminals of said another plurality of external terminals are commonlyconnected by another plurality of wires.
 4. A semiconductor deviceaccording to claim 1, wherein each of said inner lead portions extendsacross the longer sides of said rectangular semiconductor chip.
 5. Asemiconductor device according to claim 1, further comprising:an alpharay shielding polyimide film formed all over said principal surface ofsaid semiconductor chip except at said external terminals.
 6. Asemiconductor device according to claim 3, wherein a fixed potential isapplied to said common lead.